[brian_]

Pickups do offer a lot of space to work with. For examples, check out the professionally designed conversions of a couple of decades ago - the Solectria S-10 (based on Chevrolet S-10) and Ford's own Ranger EV. They don't use space in the box, but they are pure battery-electric designs, so they don't need to accommodate the fuel tank and exhaust system; however, if you have a look I think you'll find substantial space possibilities under the box, especially without a shaft down the middle and especially if you are willing to relocate the exhaust system.

One challenge is that almost all pickup trucks - and all used pickups that you can get cheaply - use a beam axle in the rear. That means to connect a drive motor to requires either complete replacement of the rear axle (e.g. the Ranger's DeDion setup, or some independent suspension) or a bulky installation which retains a driveshaft. If using a Tesla drive unit, it would make sense to choose a highly compatible suspension, since there's no usable original suspension to work around. I think you can assume that after adding a Tesla drive unit to the back of a pickup, there will not be enough room for a spare tire, unless (like the Honda Ridgeline) you mount the spare very high, over the motor.

For an offbeat alternative, if you can find an old Rabbit pickup or Dodge Rampage that hasn't disintegrated into a pile of rust, they were front-wheel-drive so they already have no rear drivetrain. Their rear axles cannot be driven, but presumably you would swap a complete independent rear suspension from a RWD or AWD vehicle under the back. They are very small as pickups go, so they might not be functional enough to be worthwhile, depending on how you would use the truck.

 

[hondarider90]

I'm thinking a custom subframe with air suspension for the back would be in order since there's going to be a lot of weight in the bed all the time, otherwise the lights would be aimed high and the truck would understeer. Basically I would be planning on doing a full rear suspension, I'm kinda picky on ride quality, my Insight is getting air suspension and it already has an Audi A8 seat that softens the bumps a lot lol.

 

[brian_]

I'm thinking a custom subframe with air suspension for the back would be in order since there's going to be a lot of weight in the bed all the time, otherwise the lights would be aimed high and the truck would understeer.

That's the normal pickup suspension challenge, but if there really was a lot of weight in the bed all of the time, it wouldn't be a problem: just set the rear ride height when loaded to match the front, and the truck body (and headlights) are level.

In practice, pickups have two solutions for this:

• they are set to be level when highly loaded (and the headlights are aimed for that), so they sit tail-up (or nose-down) when empty
• they use strongly rising-rate springs (usually leaf spring packs with overload leaves that don't come into effect until there is some compression) to get a reasonably low spring rate when empty and higher when loaded

The solution for Ram pickups with the optional suspension and for the majority of heavy trucks is the same as proposed here: using air springs so they can be adjusted dynamically.

A heavily loaded rear does not generally mean understeer. Many people look at a vehicle which is sitting low in the back due to carrying a pile of cargo and think that the front load has been reduced by the cargo, but that's not true. The front probably isn't up - the rear is just down more than the front. The tendency to understeer versus oversteer is a complex combination of tire load, tire size, suspension geometry (often expressed as roll centre height, but also including toe and camber change), and suspension roll stiffness. Air suspension changes very little of that.