If you have that level of problem with your hand then, get yourself to the docs and on to a specialist as soon as poss.
From then on, I would ditch the SLX and focus on making your life EASIER and less strenuous, it will really help:
Xtreme poles and brushes, electric reel, use 30m of reinforced pole hose on your reel, ditch the jobs that cause the most strain (cleaning over large connys) etc. It will cost you a bit to get set up, but in the long term you'll be far better off. Nice little easy houses, or better still bungalows, in and out with no stress.
Unfortunately as you get older (I'm 59) things start to ache a bit. I'm in fairly good nick but since covid I haven't exercised, so I would recommend some form of exercise; choose something you enjoy doing. I did boxing a while back (my son in law wanted to go, but not on his own) so idiot here went with him. It was actually really good exercise, both physically and mentally, but he got fed up with it so I eventually stopped too. I am looking to start some form of exercise again, I quite fancy pilates or Krav Maga.
As for retiring, it's unfortunate there are a few negative comments; but I actually think there is some truth to them. If I had my life again, I would aim to retire at 60, or earlier. I would plan in my early 20s to get a good pension (they're not brilliant but they are tax efficient) and I would definitely invest in property, especially with the onset of Airbnb. If my crypto comes in Rodney, this time next year we'll be millionaires!