How can I work on eaves of my house, 30-feet high?
I'd rent a batch of scaffolding (or "staging"), including some extensions to accommodate the berm. You can set up two or three sections and have 20 feet or more to work from at a stretch. It should be relatively inexpensive and you'll be able to keep it for a few days for the same money as a motorized lift. 

The drawback is that it's a bit slow and effort-intensive to move, but if you're able-bodied it's not difficult.