Hi Slap
I'm in the same boat as you. In recent months my work days have been limited to 3 or 4 hours a day before pain becomes unbearable.
Like yourself, I was worried about losing customers with not getting to them on time, so decided to make up with my son, who used to work with me until a recent falling out and I know rent my round out to him, with the exception of £100 a week of work around where I live. Between, what I get from the rental of my rounds and the work I do, I can live reasonably well, any spare time I have I am using to build up another round to rent out, to eventually cover the £100 a week work I have left should the arthritis get any worse.
Is there anyway you could do the same with your round? Rent it out, clean what u can and build another?
Good luck