We're getting along in years too (69 - 65) - so far between us, four hip replacements, two back surgeries, one knee, one ankle (twice), and we refuse to allow pain and age stop us.
We're heading out for a cross-country trip today ... We do have occasional issues setting up, but always ask the ranger or the host for a hand if we need it, and they're always willing to help and gossip.
SO, renting at first is a great idea, but don't rent long-term, rent, go for it, test everything you'll need to do, several times, and ask for assistance from the neighbor, the host, or offer a teen a couple bucks to set you up - teens usually know everything if they're camping too. Then, go for it, and go where you want, when you want.
We have never had an issue that stopped us, so don't let it stop you if you really want to continue with RV ... you don't have to move often, just find a spot you enjoy, hang around for awhile, then get a little help and move on.
Good Luck and happy camping ... M44 & Genie
