Could you be more specific? What about this proposed "ideal" scheme is infeasible (specifically the engineering limitations you mentioned)?
If I’m out in the middle of nowhere with my team and we’re using these radios because there’s no cell coverage, a) how would a given radio “bid” on a piece of spectrum, and b) how would the other units in the talk group know to listen to a particular frequency for my message?
Right now it’s easy to know whom to tell about the coordination though: the Canadian government :).