I am not wheelchair bound but I can't stand. Standing for any amount of time makes me sick. I also have very bad knees so sitting is a must. Just walking 100 feet on crutches to my shop is a challenge.
I'm still redesigning my smithy and will get some pictures later but the first thing I did is come up with a chair. My legs must be level when sitting. Knees too high or too low causes problems and I'll probably find something that works better eventually but for now I welded a pipe to the inside curve of a disc harrow blade and have a cushioned boat seat mounted in the pipe. Takes a little getting used to but I can spin around, lean forward, backward and to eather side.
With my forge in front of me I have a post anvil to my left, my old London pattern to my right and my vise directly behind me. Like TP said earlier, I like my anvil between my legs.
I'll get some dimensions later but I used a block of wood and my hammer to get anvil height. I would hit it and cut it off until I got a perfect hammer face. That's the height of my anvil face.
I'll add more and pictures later. Hope this can help somebody out there. It works for me.