Hi,
My husband was in a wheelchair for years after a stroke. What sort of chair are you using? A lightweight sports type one with some spare parts just in case would help if you can get one.
Also, what ever your vehicle, get some good solid hand holds bolted or welded on here and there, inside and out, to assist if needed. One thing we are still planning is a sort of subway strap series in our van, to help hubby
walk without his quad cane. Maybe you can put something like that up to assist in transfering from bed to chair and so forth? Or make the build so snug you can get around inside comfortably without the chair? I hope that give you some good ideas. And remember to get those half price camping passes for handicap. Hubby was over the moon about that.
Don't let anyone tell you "You can't".