I think that while what you propose is certainly doable, that it will take a lot of time, effort, and money to do it right.
I'm planning a roof raise (this spring I hope), and plan to eliminate the wheel hump problem by building a secondary floor inside, higher than the wheel humps, with steps down to the drivers area. I will keep my tanks between the two floors, with them kept inside the thermal envelope. I will also use that area for extra storage, etc. I don't know yet exactly how much that floor will be above the existing floor, but I'm thinking somewhere between 12" and 24" up.
The basement area under the original floor will have fuel tanks, propane, battery banks, generator(s), and some exterior accessible storage.
My goal is to have plenty of headroom, and also keep my center of gravity as close to the ground as possible. I also want maximum comfort.
I also plan to have an extreme amount of insulation. But that's a story for a different thread.
Good luck with your conversion,