RE: CG <-> Down thrust relation?
I set the CG as far forward as I can. Basically pull to 45 degrees half roll and see what happens. If it noses over move the CG back, if it climbs to the belly add nose weight. I like mine so it will, ever so slightly, nose drop.
THrust line is simple. Get the wings level and pull vertical. See what the nose does, add some rudder trim, but as it slows down you'll see if it pitches to the belly or canopy. Add up or down thrust as appropriate so its hands off on the vertical upline.
Thats it!
See you,
Don