I wonder if something like DupliColor's Truck Bed Coating would work?
Go over the OEM paint with red scuff pads then wash it down real good with something like Simple Green and let it dry, then paint.
It is a black vinyl polymer so it would hold up to weather real well, bird crap wouldn't effect it and there'd be no need to wax. With a little bit of texture to hide blems, the stuff would be durable as heck. Brush and branches wouldn't phase it and if they did, touch-up is easy.
They have a spray kit for use with a compressor, you can roll it on, and it also comes in rattle cans.