You can rent a scaffold and get close to base to remove/replace fixture

Your concern is a bit similar to my recent post, since I, too, want to replace a fixture that is attached to a vaulted ceiling area. Same exact problem here...really can't just lean a ladder along the wall, and yet to bring in my 15 ft. step ladder to try to get up there to clean the fixture is just such a hassle. To clean it involves taking off a glass cover that is open at the top, and then the bulbs are underneath that. The few times I've done it I'm petrified that I'm going to drop it. If that would happen, it's going to go off like a bomb at the bottom of the foyer and smash all over the place. Also, I'm not as fond of heights as I once was!

As to your specific question, I'd be inclined to hire an electrician to remove and replace the fixture.