Kirk:

On the Super Duellist we decided to put the flaps from #2 rib to #6 rib. BUT, since the SD is a modification of the Duellist Mk II it has more ribs than the Mk I, so you would then run them approx to rib #5, the first one outboard of the nacelles. By mixing them in as "Flaperons" you still have full control, and when in use as flaps the prop wash will have full effect. With the flaps as short as you proposed I doubt they would do much for you, and just add weight to the airplane.

The airplane is a low wing design, so for neutral characteristics upright and inverted it needs a bit of dihedral. As designed it's just about right. I'd leave it alone even if you do 0-0-0 the hard way by remounting the wing and stab.

One change I do like is adding shear webs to the spar to the rib past the nacelles, doesn't add a lot of weight but does add a lot of strength.

Bill.