It's hard to see in the sketch, but the stabilizer has a small amount of dihedral, like a V-tail. The inverted fin forms the bottom leg of the Y-tail. There's no real benefit to this tail arrangement, other than its unusual look. To me, that's a benefit! The canopy/turtledeck (which I would probably enlarge if I actually built this model) is drawn as a flat sheet of balsa for simplicity. I love simple. You might also notice that none of my tapered wing designs use a straight trailing edge (viewed from above). Most of them use a straight leading edge, like this one, or something in between. Although it may offer some aerodynamic advantages, a straight TE with a swept back LE is a wing planform that has never looked good to my eye (well, actually, both eyes).