Does the bow bend in the tip area you intend to flip? I would go for the 20 degree bend, and as short a length as I could get away with (maybe 3 or 4"). That'll improve your string angle enough, and it won't pull out if the tips are still somewhat stiff. If the bow is bending through that area, you might have to bolster it a bit with some extra sinew.
I'd boil the tips, they'll get hot enough faster. And you might want to strap the belly so it doesn't splinter, though a modest bend might not require it.