Austro, yes, aging is definitely not for the faint hearted.
I rode my son's Super Glide here in Hawaii and have the same problem. He has footpegs mounted forward in addition to the stock. I ride most of the time with my feet on the forward pegs and then find it a challenge to move my foot back to shift or put my foot down. .
I am under 6 ft and since the Rocket sits higher I don't have the challenging of shifting my weight to move my feet back. You might consider a higher seat like the Russel Day Long and a set of longer Progressive shocks. Unfortunately it would cost about a thousand bucks.
It would take your mind off the pain in your legs so you could concentrate more on girl watching, which we are never too old to do.