all in all there is about 6 meters high by about 5 meters wide. the central area is going to be a [ I should have amended this post ] .
thought about some sort of extention but isnt it then difficult to avoid lines?
No, not if you work on your technique. I clean trad' up to that height & beyond. It gets more difficult the further you go, but it's doable with a good result. You could also pay a local wfp user to do your problem windows - another way to network.