Sounds good; thanks for the guesstimates. The top and bottom angles should come out to approximately 15 degrees. If it doesn't work I can always add an inch or two under the back plate and lower the bottom. Tuft testing will happen as soon as I get it together.
I'll have to look up the boat tail data, or maybe just wing it and see what happens.
I picked up a fiberglass temporary fence post, small hinge and angle bracket at Fleet Farm. Should be able to mock up that backup aid after some other details are worked out, but before I skin the tail. Still need to get more 8' aluminum bar but everyone's sold out (I wonder why
)