RE: Adding Air Breaks?
Not all high wing planes are created equally. A streamlined fuse design acts very different from a big round cowl design. A large amount of frontal area (such as the mulligan has) like a P-47, cessna 185, and such can slow the plane down quickly as soon as you throttle way back. Flaps are a great idea. Spoilers or dive brakes wont do you much good unless you have a very aerodynamically clean design like a high lift sail plane. They use spoiler/dive brakes to make sure you dont over shoot your landing zone. It takes a fair amount of skill to manage you lift to the landing zone. You dont get much of a second chance without an engine.
Edwin