Cub:

That's a good thought. Build the wing attachment to allow either side up. One way it's a trainer, and if you can stand the razzing, the other way it's an aerobat!

Or you can build it with zero dihedral, and put an amount of sweep on the leading edge.

Believe it or not, a swept leading edge, with a symmetric airfoil and zero incidence gives aerodynamic dihedral. It works because the nose is always up slightly in level flight, upright or inverted.

Just more to think about.

Bt always have a fin, on your flat single or twin.

Bill.