sportcoupe since you are in planning stages is a good thing, many fail to plan or think things out and you get what you deserve. Allow me to point a few things out, and what I have learned in my career.
First thing will strike you as odd, but for now forget AMP HOURS. Jest get that out of the equation and consideration. All it will do is cause errors. Amp Hours is a end result after all the calculations have been done. It is the LAST CALCULATION. In fact it is not a calculation, just a simple Conversion.. You are not consuming Amp Hours, you are consuming Watt Hours which is the real work, energy used, and what you use to calculate everything.
So the very first step in the process is sit down, be careful what you ask for, and determine how many watt hours you need in a 24-hour day. It is pretty easy to do. If you are not sure, ask. In a nutshell find how many Watts each gadget and gizmo uses, and then multiply by the number of hours you expect to run it in a 24 hour period. Example say 50 watts x 3 hours = 150 watt hours. Add them all up and say you get 1500 Watt Hours per day.
OK Solar and RV's I am afraid to say are very challenging. They do not play well together. There are many obstacles to overcome. To determine panel wattage all data sources assume ideal conditions, and in an RV you cannot even get close. Example we are looking for Sun Hours. Depending on where you are at and time of year can vary. In general 5 Sun Hours in Summer, and 2 to 3 in Winter. That assumes absolutely no Shade Issues from sunrise to sunset, at optimum tilt/orientation angle, at moderate cool temps. That would mean parking in Full Sun with no shade in eye site. Park at the perfect angle to orient panels solar south. Then have a way to elevate the panels off the roof so they can stay reasonable cool, and provide the proper tilt angle. See any problems doing that, and be confident you got it right? Good luck with that.
But lets say you did get it right. What panel Wattage is required? That is where we need Sun Hours and Daily 24-Hour Watt Hour Usage. If you want to pay more money than necessary, use an inexpensive PWM Charge Controller. If you use a PWM Controller Panel Wattage = [Daily Watt Hours x 2] / Sun Hours. Example 4 Sun Hours and 1500 wh. 1500 x 2 / 4 = 750 watts minimum. Did you ask yourself why PWM is more expensive?
Now if you want to save money, make things efficient, less material less space required, use a quality MPPT Controller. They will cost you 5 times more than PWM. OK with a MPPT Controller Panel Wattage = [Daily WH x 1.5] / Sun Hours. So 1500 wh x 1.5 / 4 = 562 watts. 550 watt sis close enough.
As for Controller is easy. Run through the MPPT panel wattage 550 watts. Minimum MPPT Controller Amperage = Panel Wattage / Nominal Battery Voltage +1 volt per 12 volt of battery. You already know 12 volt battery + 1 volt = 13 volts. So 550 watts / 13 = 42 amps so you are looking at a 40 to 45 amp controller minimum for either PWM or MPPT. They both wil delive the same current, PWM just needs a lot more wattage than MPPT.
However that is not the only place you save a ton of cash with MPPT. If you use PWM you must, and I say MUST use very expensive low voltage 12 volt battery panels. You must also wire all the panels in Parallel. Two last things you never want to do. Low Voltage battery panels wil cost 2 to 5 time $/watt of Higher Voltage Grid Tied Panels. Being lower voltage means smaller wattage panels. 180 watts is about as big as 12 volt battery panels come in. At 750 watts means 5 x 150 watt panels wired in parallel. Once you have more than 2 parallel Strings is going to require expensive Combiner, and Fuse/Breaker assemble. After Combined you will be running 45 amps to the Controller Input which requires some heavy 6 AWG cable to figure out how to run in. Also mean racking hardware x 5. Not what you want to do and the biggest error almost all DIY's make. We call it Stuck Inside A 12 Volt Toy Box mentality. Don't do that.
Smart Money is to use much less expensive Grid Tied Panels and MPPT Controller. GT panels run at much higher voltage which means much lower current and more panel wattage up to 300 watts per panel. All you need is two or three panels all wired in series. Example use 2 x 275 watt panels = 550 watts. With the panels wired in series panel current to the Controller Input will be around 9 amps which means a single 14 AWG wire, no fuses or combiners to deal with as they serve no purpose. I use a 20-amp cartridge type at the controller Input for a Disconnect Device. Otherwise if required like PWM to be located at the source; the panels.
OK all the work is done, what size battery? Well again we need Daily Watt Hours, nominal Battery Voltage and most important number of all is HOW MANY DAY RESERVE CAPACITY. In a stationary system would be a 5-Day Minimum reserve. In real application gives you 3 to 3.5 cloudy day coverage before you run your generator. Determined over years 5 day sis the sweet spot economically getting the most bang from your buck making the batteries last as long as they can yielding maximum energy storage.
But you are not going to do that. Not required for an RV. You do not use them every day 7 x 24 x 365. RV minimum is 3 days with or without solar. That will give you two full days of run time before you need to do something. Rest is easy and as promised Amp Hours is just the end result with no mistake and taking Peukert, Charge Efficiency, wire losses , and all losses have been accounted for. So now we know daily wh, battery voltage, and reserve time. Battery AH = Daily wh x Reserve Days / Nominal Battery Voltage. So we have 1500 wh x 3 / 12 volts = 375 AH
However forget all that work. We used optimum conditions you have no way in heck to do. By the time you de-rated everything from ideal would require well over 1500 watts of panels. Two real expensive charge 60-amp controllers at 12 volts. A lot more current than FLA can take, but AGM could if money is no object.
Make it easy in an RV determine daily wh, 3--day reserve capacity. Find Capacity which is the same 375 AH battery. Accept the fact Solar is not going to be your primary power source and treat it as Supplemental Power. Use an Electronic Battery Isolator to allow engine alternator to do charging. If driving daily or every other day will be your primary power source assuming you are driving a few hours. If you add solar can add a day to that. Carry a generator and charger. Size Genny to run the loads and charge battery at max rate.
Want solar with that? Easy peazy money bags. Size panel wattage and controller to supply roughly C/10 charge current or as much as you can afford without going over C/8. No need to waste money on something that is not your primary source Panel Wattage = C/10 Current x Nominal Battery Voltage + 2-volt per 12 volt battery. 38 amps x 14 volts = 532 watts. 2 x 250 watt panels and 40 amp MPPT Controller. Even with Solar still requires a generator and/or driving if you spent that $75 on an Electronic Battery Isolator.
Last comment on the RV battery type. 3 days FLA, AGM, LFP, or ABC--123 makes no difference. All will work with above.
So go figure it out.