We used to operate a peg-off, card-on scheme.
the peg board has a clip that goes round the antenna with the channel number attached. The flier removes the peg, attaches it to the antenna and puts the club membership card on the pegboard. No transmission without the peg!
That way, anyone transmitting should have a peg and if the channel's being hogged, you know who to go to.

We don't operate 2.4GHz in the same way, we just put our club cards on the peg-board.