Flyerjohn - there is another modeling organization that provides primary insurance coverage - they go by the name: "United Modelers Association" - and they have a website located at the following link:
http://www.unitedmodelers.com/
I don't know much about the organization, but I have seen several folks discussing it - and it appears that it may be the type of an organization that you and your club are looking for.
I hope that helps!