It always mystified me why folks would buy Flite Streak kits and then leave off the good bits that improved performance- the tips and the flaps. They added a bunch of area for minimal weight.
The original Barnstormer, about 1950 I think, and the Flite Streak, a few years later used the built up wing with a fixed flap. It wasn't until maybe 10 years ago several people looked at that kind of airfoil with XFoil. The configuration was also tested by NACA. Turns out the thin, fixed flap actually produces more lift than a smooth, symmetrical airfoil without the separate flap. Which is a big reason why the stock Flite Streak can fly as well as it does.
I'm kind of surprised that F2D guys haven't used something similar. The current planes are essentially One Design combat with only two variations- whale tail with an attached flipper vs. a stabilator on a small extension, and either a straight trailing edge or a curved one to add some square inches.