I agree with Eric that the CQ time limit probably wouldn't work. (It was
just the first idea that occurred to me.) Eric is also correct that the
real problem occurs when lots of loud stations are calling CQ without getting
many answers. Limiting the number of CQ's without responses to two sounds
like a much better idea. The only problem I can see is that it might
encourage loooong CQ's. Perhaps something like a maximum of 60 seconds
without a response would work. I'm not sure how to handle the clock
reset in the multi-op and two-radio cases.
I guess I wouldn't worry too much about enforcement. Peer pressure would
probably be sufficient to get a high enough level of compliance to accomplish
the goal here.