Hi Joe
i use an unger optiloc pole converted to waterfed which is also 18ft and find it great also with windows above conservatory,s i find i clean most of them from either side of the conservatory or if i do have to go right over the top i just change the angle of the brush on the angle adapter.
must admit that i have been thinking about getting a 24ft carbon pole just the thought of spending a money does nothing for me when the unger pole does the job and replacement locking clamp,s are cheap enough........
darren