kind of a kooky suggestion but i think the best way to know how difficult it would be to grow while in a wheel chair would be to experience it.

I also think some ways of growing would be easier than others. Like with what you said with hauling abunch of water. and also your handicaped friend might want to train his plants not to grow so tall; so he will have an easier time inspecting,harvesting, and just seeing his plants.

im interested in how everything works out. good luck