Dean can't you just get a polo with 'window cleaner' wrote on it? That way you will at least let people know your job when you don't have a pole or squeegee in your hand an you may even get away with having your number on it.
I have polo shirts with my company name front an my own name, then on the back I have my company name and my number cost me 11 each with the printing on it, also got some smart cargo pants and shorts as well as jumpers an hi vis's