Is the plan to keep this a 4-door, or to convert it to a 2-door?
The reason I ask is that it seems like you can get more body taper if you start more forward, but you lose much utility.
https://jalopnik.com/for-10-000-is-t...d-s-1789661546
https://www.carscoops.com/2019/01/ol...ans-gladiator/
https://www.reddit.com/r/****ty_Car_...erokee_pickup/
I view this project as much in the spirit as the SUV to Pickup truck conversions links above.
And in that sense, making this a pickup truck with an removable or hinged aero-cap may allow better access to the aft spaces.
Just food for thought, I still think this is a solution to the question never asked but cheer you on in your resourcefulness.