You didn't get a business plan. You got a marketing strategy.
You CAN operate the Leaf from a single external "module" - lots of people here are using the Resolve controller to exactly do that.
You would be smart to have temperature, voltage, and other telemetry to be able to do PM during charging, unless you're show vs go.
The beauty of what we recommended is little to no mechanical design, other than perhaps adding a few modules to the top of the pack to overvolt the motor.
The car would be stripped of everything but its essentials, but the battery pack and drivetrain are as God, and Nissan, intended them to be...that is THE most RELIABLE build convergence in what's been on the table so far and reliability wins endurance races/rallies. Budget and time is better spent elsewhere than cribbing some angle iron mounts up whose welds will break and spill battery guts all over the road course.
What I would do from there is add a few modules to the top of the cell stack to overvolt the HV section by 10-20%. Run 20% overcurrent and you're close to 300HP.
Your build plan allegedly is open for change in any direction, except, of course, for that being recommended here by everybody 🤓
That widebody design, by the way, is gluing foam blocks to the car and shaping them with a knife and a surform and carbody sanding tools. The concept pic I found is a great guide and fortunately doesn't have compound curves, though I'm sure you can easily find an artist or bodywork person to do any sculpting quite easily using this method. From there, a layer or two of carbon fiber or fiberglass, some filler, paint, and you're good. Lots of people would line up to do that build as volunteers, vs working on their mom's Honda Civic that doesn't feed from a nitrous bottle.
I will continue to make corrections, like to your module misperception...none of the original Leaf control or operator interfaces would likely remain working and would likely have been stripped and a Resolve controller would run the drivetrain show, like it would have in the Civic.
Unlike the Civic, the work is substantially reduced, and reliability is orders of magnitude higher if you leave the drive unit and battery pack in the car. Chargers, charger port, public charging ability all stay with the car and should continue working.