If you could make a trailer that could carry, say four 25ltr containers, that could give you more work time.And i don't think it would be to heavy to push.
Not sure you can compete with the reach and wash window cleaners if you are using a extendable pole and squeegee. How will you clean the frames from the floor, and get to awkward windows?
The best way I think you can do it is this way. First, clean from ladder and do frames and then from 2nd...