P'raps there is an answer:-
Separate out the business of airworthiness into a wholly owned subsidiary that is run on commercial lines with a proper management structure. PFA as owners task the management team with producing a commercial rate of return on the investment but is not involved with the day to day running of the organisation.
Those who own or are building Permit aircraft do not then have to be members of the PFA but pay the same amount and become customers of the airworthiness business. If they are aggrieved then their remedy is the same that it would be against any other company.
The PFA itself is then a separate members organisation that runs the strut system, the Magazine, the Rally, Young Eagles, Coaching Scheme etc. Those who are members of the PFA have a voice as members and are there because they choose to be rather than because they have to be by virtue of having bought a Permit aircraft. If of they break the rules they can be expelled just like any other club.
Mike