Hi There Solo,
Sorry to read about your back problems buddy .. but at the same time I'm pleased that you are taking the best 'course of action' to deal with it .. good man .. be strong.
You really can find a way 'around' most Physical problems and still be a Biker (of sorts) if you really try. I remember the one armed guys who rode solo Fireblades around the IOM .. faster than I can eat a Full English.
It's not about riding like Bob McIntyre or even Cal Crutchlow .. you just can't play at doing that kind of stuff anymore. It is about the pride of ownership, the freedom of the road, wind in your hair (I had hair once :\ ) and above all about being part of a this fantastic international clan ... and you can do all of that. I do.
As you say .. at only 47 you are still just a nipper (I've got kids older than you) so you need to stay focused and realistic about your ability, the kind of bike you ride and the sort of biking you do. There is no need to give it all up just yet !
A duff back is (of course) a real pain in the butt in more ways than one (welcome to the club mate) even more so if you have previously been the action man type .. but you can overcome much of the aggro by adjusting what you do on the bike.
Only when the problems start to involve your Brain Box and therefore the general safety of other peeps .. is it time to call it a day .. all just my opinion of course 8) .
Like I always say .. Stay Safe

Polar Bear (Spain)