Not to be insensitive, but what exactly is the dilemma? If the county requires some form of insurance or another in order to fly, the exact form the insurance shouldn't matter too much. As an individual, all you need to know is that the people you're flying with are each covered, so that if you're involved in a mishap with them there will be coverage for all parties. If the county chooses to forgo the benefits of the AMA's landowner policy, that's just their choice to make.

So long as the county has proof of adequate insurance before they issue a field permit, nothing much should change. That's the situation the field I fly at has been operating under, and we have no problems.

One thing I would suggest is that your club recommend to the county that they not attempt to do the AMA days/non-AMA days schedule. That sort of thing leads to a compromise that only works on paper. Somebody will show up on the day that isn't theirs, and who enforces that rule? It creates an artificial "us vs them" and creates the potential for an artificial conflict as well.