Well I'm 61 only one year behind you and use one of these
http://www.amazon.com/s/?ie=UTF8&keywords=xtend+climb&tag=googhydr-20&index=aps&hvadid=31558819757&hvpos=1t1&hvexid=&hvnetw=g&hvrand=11920726583587616613&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_7fk1yn4s39_b Hated to pay the price but I also needed ladder and this took place of the bunk ladder and roof ladder and I also use around house sometimes. I didn't want a RV ladder installed because I couldn't tell where support was on top to screw into. One day at the local Sherwood Williams paint store I saw it, went home and read reviews. They are not perfect but better than drilling holes in roof guessing where support beam was IMO. I also take the ladder around to the sides of RV instead of standing on a roof in slippery soapy water when washing. I got a bigger rating even though the rating of my weight was OK, wanted to make sure it would be OK if was lugging something up on roof. BE advised... Has served me well
after I learned to turn it upside down to close instead of pinching my fingers. Towel or old rags around top keeps any scratches off RV. If you check one out at paint store measure width first. Mine barley fits with sofa made out into bed. I would buy again. I do ask wife to steady me on any ladder, or at least have phone ready to call 911:)
Amazon has them but wanted to buy locally in case I didn't like and pretty big to ship back. Camping world has a ladder that folds up and can fit into vinyl fence post on bumper, but not long enough IMO.
Ok my 2 cents worth
(edit part...WOW looking at above posts, seems I'm not only one that like extend-a-climb)