Just read your post John - Last job!
I've been trying to escape the business for years, for similar reasons to yours, but have yet to sell my main equipment.
Like yourself, I've been trying 'Charlies' and Dry System cleaning, purely as a means of continuing to earn regular money, but, I find the Rotary, can be more damaging on the back and have still to try a couple of lighter machines, eg, Contra rotating brushes, either barrel, or rotary types.
Used a Klanz in the past, which has two 'floating' contra rotating heads which can be used with 'powder' or 'microsplitter' and on hard floors.
Due to the state of my skeletal structure, I must stop heavy lifting and the Klanz, or Host type of machine would allow me to continue, but, change can be hard to accept...............
Best wishes
robert meldrum