For trad I use a wagtail on a Harris pole occationally, that's only 15 ft though and to be honest it's about as high as I would want to go. That's commercial jobs high up inside, so in actual fact these windows will never get inspected closely. Your speaking about cleaning people's bedroom windows, its not going to work out that well to be honest as you won't be able to give a quality clean.
If you really want to give it a go though, I'd say get a carbon fibre wfp and instead of using the brush, stick in some trad tools. I've done this once or twice with my slx, it's about the best your going to get but not a cheap option(£300-£400). You might as well get a back pack and carry some barrels of pure water and do it properly.
Simon.