Queen, while I haven't had a knee replacement, I am finding that my body is sadly out of shape (unless you consider round to be a shape...
). I have trouble bending over for any length of time, look like a turtle when trying to get up and down from a sitting position on the floor etc. etc ad nauseum. Oh, and I'm too short to reach what normal people can! Confession time, I'm 66, female, 5' tall and need to lose more pounds than I'm willing to confess to.
I do most of my 'construction' work on a 2' x 4' table. When the screws that hold the folding legs were bothering the good plywood, I took some scraps of foam and taped them over the screws...now the plywood doesn't skitter around and I'm not damaging the plywood. When I wanted to cut lauan I found that it could lay on the van floor and I pulled only what I needed out the back cargo doors.
Most of the insulation work is measuring and cutting. Since I work alone measuring from the floor up took a little ingenuity to get the tape measure to stay in place. A little piece of wood with my foot on it held the tape measure in place. I did most all my installation sitting on a stool. It kept me from being bent over and kneeling is just about out of the question although those knee pads are one of my favorite tools.
What I'm basically saying is that a little bit of ingenuity and some adaptability can overcome most all but the most serious of 'disability'.
If you can get in and out of the van, even with a step stool, which by the way I use two of, one inside to sit on for work, one outside to get in the side cargo doors, then you can most likely figure out how to get the job done. And ask if you haven't been able to figure out a tactic on your own....I've probably already encountered it....
Oh and when I ran into something that was just too difficult, I hired the teenager next door. It was the stupid caulking gun that my arthritic hands couldn't deal with. At $10.00 an hour, he was a godsend. He'll be back helping the next time I run into something I just can't handle.