The idea has a lot of potential - I've pondered it as well, though the airspace in my area (Greater Vancouver) is way too busy, and the local field locations are in built up areas for the most part, preventing flight down to 500 AGL (field neighbours would get pissed). Ah well.
Your idea seems workable. Just keep in mind that it's all based on the ability to communicate with someone on the ground via radio. You may need to test this out beforehand, as well as secure permission from the aircraft owner prior to using non-aviation band radios inside the aircraft. The blister-pack GMRS radios likely won't have enough range to reach an orbiting aircraft, whereas the more powerful UHF radios (carried by the passenger) may cause interference with the aircraft's radios and navaids (though I'm not 100% sure if it would be an issue). As well, check the CARs regarding electronic device usage before you do anything, just to be sure.
I like some of your scenario ideas - they would work well in a longer milsim (i.e. weekend-long types). Larger games would help offset the cost, where a small portion of each entry fee could go towards paying for the flight time.
Hope your plans come to fruition sometime soon - Cheers!
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