I feel your pain. My garage has 14' high ceilings. For someone who is petrified of heights like me, changing the bulbs up that high are a pain in the butt. Just get a really good sturdy ladder, although I'm guessing you already do if you've been mudding and taping up that high.
Ladders on scaffolding
I have acrophobia, so I'm not the one on the scaffolding or ladder.