I sympathize with the OP big time. At age 76 and with genetically flat feet, significant arthritus and sciatica, I've looked for solutions to several of the same problems the OP and the others mention. I shoot a 5D3, and even with the lightest lenses, I simply cannot handle the weight on an ordinary neck strap.
So rather than going through a dozen or more shoulder/neck strap combinations that won't work anyway, all at significant expense, I've rejected that type of strap completely. Instead, I use a hand strap [currently a Canon, but with a Camdapter on the way] that gives good support to my right hand, yet allows easy use of my fingers.
Then, instead of trying to hold the camera constantly, I use a Lowe Pro Roller Attache X 50 bag. It's on wheels and easily handles my 5D3 with lens attached, a second lens, a flash, spare batteries and cards, and several other small accessories. If needed, I can stuff another mid sized lens in on top, but I seldom need one. The outer shell of the case is pretty stiff, making it easy to strap my tripod to the top whenever I want to take it along. What makes the case so convenient is that it opens at the top with a double slider zipper, hinges at the bottom, and with the zip undone all the way, the bag stays open without trouble. I generally leave the cam in the open case as I move around, then just grab it out of the top when I need it. If the terrain is rough, or there are others around and don't want the cam exposed to their view, I can close the zips a bit and close the compartment a little or all teh way. Thus, all the weight is in the bag except for the few minutes I actually hold the camera while shooting. Moreover, this thing is a convertible. That is, the part that actually contains the camera gear, can be lifted out of the roller base and converted to a shoulder bag, if needed. I've never needed it that way, though. When closed all the way, the bag easily fits in the carry on space on most [all?] planes.
This system works well for me and allows me more time with the camera. I'd suggest taking a look at this bag and a hand strap. Incidentally, one of the accessories I always carry is a bottle of Tylenol Arthritus Pain Relief 650mg strength.
Good luck to all. Whatever you do, I hope you can resolve the problems and avoid the aches and pains that keep you away from doing what you want to do.