Need help with come up with a idea to clean rail

Hey everyone! I could use a little help with a project. I was asked for a quote to clean all the railings on the balconies – there are 72 balconies over eight floors. So, I’m wondering if anyone has ideas on how to reach the highest floor without having to scale down? They’re looking for cleaning every two months. Thanks!

The best and fastest way i know of is using a pressure wash drone,

Hang off the side with something to scrub it with and a hose from the roof to rinse it