I make my midget stand on my shoulders and polish the roof.....
Seriously, I'll flip a 5 gallon bucket upside down and stand on top of it, or open the doors, take my shoes off (so I don't mess up the interior I just cleaned), stand on the door jam, hold on with my left hand and use my right hand to run the DA. Can't do any real correction work or polishing using only 1 hand. You're only laying wax down, but it's the roof. As long as it's not horribly swirled beyond belief, I just want to put some wax on it as a protective measure.
I posted in a thread a month or so ago about this very same topic, and there was significant discussion about the very real dangers of slipping and falling or having the plastic bucket crack and break. A step ladder or scaffold is one of those things I'll get around to buying eventually..... It'll probably be the first thing I buy once I slip, fall, break my arm, and am out of work for 6 weeks.