RE: Pusher engine thust angle Question
I'd tend to try it as the plans show it first. That is equivalent to a bit of downthrust on a conventional tractor layout. Now the resultant between the drag forces trying to rotate the wing into a more positive angle of attack and the engine trying to force it into a less positive angle, the forces will balance out at some speed. If you do not have any of the downthrust, the faster you go, the more it will want to pitch up.