Well that is crappy. I know exactly what you are going through, as we looked at Class A and Class C about 4 years ago. Still have the camper and use stools to make steps shorter, but she still loves the camper, so I am in charge of making it work for us.
She is in line for two new knees, but Ontario just put another hold on elective surgeries, so who knows when the new knees are going to be installed. Next it will be supply chain issues for replacement parts!
Your wife could try cortisone shots many people have had luck with them. My wife's surgeon said not to do them because of fear of infection before surgery.
Sad that you will be losing your labour of love. Good luck in your search.
Brian