I just spent the last 2 weeks replacing rafter tails on a house between rain days and other distractions. Rent some scaffolding?, good idea. I rented 2 bucks. Peeled back the roof and made my splices in the attic spaces. I had to brace to the joists and gusset everything.
The best prevention I know of is to use *wide* drip edge, and aluminum fascia. Even without gutters, this will keep the water away from the wood.
Tom in KY, 68 degrees last week and an inch of snow last night....?