Duck, if you make the model light enough that it flies at the speed you want and chose an airfoil that works nicely at that speed then I fully agree with your use of split flaps for drag only. They still add lift but likely nowhere near what a standard flap would provide.

Of course if you can make it light enough then almost any airfoil will be fine.

I also second the idea of adding 2 or 3 degrees of dihedral to this design. It'll help the stability and also prevent the "tired wing syndrome" that seems to go hand in hand when you don't have any dihedral at all.