I'm 69, and my body is starting to give out from use and abuse in my younger years. I've been a full timer since 1964.
I have a low top van, with a comfy swivel/rocking/reclining old school type executive office chair. I basically do everything while seated. I can sit straight up in my chair, on my toilet, or while showering, and I can sit straight up on my bed. I guess you could say that I scoot between them, because I am rarely on my knees or hunched over walking.
I can stretch out on my bed, or in my chair and put my feet up. When dressing I do a simple bounce either on my bed or in my chair, in a seated position, to pull my pants up.
Basically everything is within easy reach of either my chair or my bed. If I choose to stand and shower, I can set up my version of a shower tent at either my side or rear doors.
If I feel the need to stand or walk, I have the whole outdoors at my disposal. For me, regardless of how much headroom I might have, I am still going to be spending 95% of my time indoors sitting down, and adjusting that last 5% of my time, like cooking or showering, into a seated scenario was a very easy adjustment.
I don't find living in a low top van to be limiting in any way, not even comfort. I believe that I can and do, do everything that I would do even in a conventional house. If I need to work on a project bigger than my house allows, then I do it outdoors. If needed, I will do it under a canopy, and it needed, I can enclose that canopy. The same as if I didn't have a workshop in a house. I have a generator and inverters, to run any power tools or anything I might need.
Living on the road has never been about doing without for me, it's about having more, and living better than I ever could in a normal house. Living in a low top van vs. a high top or a larger RV, only requires a few simple adjustments that are easy to make.
Cheers!