There is a video of a guy who built a reversable glow engine prop setup and it shows it flying. It was a complicated and heavy modification. It can be done.

What I would be more interested in is a constant speed prop. I have plans for one for a 1/6th scale P&W Wasp Jr engine, but the issue is the prop blades. I can purchase carbon fiber blades, $90 a pair, from the deisigner in Australia, but these are not the size I need for my flying, 19" vs a 14" for most of my planes. The hub is not a complicated devise, but it will add maybe 4oz on the nose of the engine and then comes the issue blade manufacturing for the size you want. I'm not sure the cure isn't going to worse than the ailment. For the time being I'm on the sidelines looking. The though of a 5 to 15 pitch is interesting, but only for all out speed.

Don