Those would have to be set up like Quad races. Not sure how that would work FPV as 25mw would not cover a field large enough for a fixed wing course. Flying at 200 mw or more with pilots sitting in a fixed area might cause problems with video management. Just something to think about. May have to run it time trial style to be safe. Or maybe at best two planes per heat.
Then on top of that there would have to be a HUGE safety crew to cover all points of possible entry onto the flying course. Running fast and low exponentially raises the chances for hurting soft targets. Planes arent like quads that can pull up in an instant should one wander into the flight path.
Just a few things that pop to mind about the organisation side of this.