Definitely feel for you!
Firstly I would say its pretty important to be straight up honest with your doc or physio about what your doing, if you dont trust your doc enough to be honest with him/her then get a new doctor.
I'm a lot younger than you (as in half your age) but a previous sporting past combined with a bit of bad luck has left me with arthritic pains I shouldnt have to worry about for 50 years:
Snapped right ankle, snapped left tibia, snapped tibia again, ACL reconstruction in left knee, chronic tendonosis and torn patella tendon in right knee, broken rib, broken rib, broken rib, snapped collarbone, snapped collarbone again, cracked shoulder blade, x2 compressed vertebrae in neck, dislocated left wrist once and right wrist twice, a cyst has developed in my right wrist joint, 3 severe concussions and on top of all that I have a spinal disease that places huge load on my lumbar spine and is untreatable.
All of this equals huge amounts of pain on a daily basis. But i actually find the worst pain is simply from lugging the rig around on my back. Joints all ache after a day of walking let alone skydiving, kickboxing, gymnastics, hiking etc.
I guess what Im saying is you gotta know the juice is worth the squeeze. Provided your not causing any further damage by doing what ever, then you just have to decide if the pain at the end of the day is worth the life changing experiences your getting yourself into each weekend.
Sorry i know im not much help. Stretch, exercise, yoga, diet, pills, big chutes, it will all help.
Enjoy it now coz you cant when your in a retirement home...