If you're not comfortable walking that roof (it is steep and high) then just shoot from the ladder. If you put it to the top of the dormer on the left you could shoot that whole side from there.
You don't need a lift for that. A Delevan will work fine on that house shooting from the eaves as long as you don't have a strong wind blowing.
The Delevan will work.The roofs out here are usually 10/12 or 12/12 pitch. Will the delevan pump work for this application? I have not had many roof opportunities.