If you are allowing visitor parking to be used for extra resident parking, you are probably in breach of your Development Approval.
If it is only allowed with the written approval of the committee, change the rules so that each person who applies has to register the rego number when they apply.
Do an “audit” of cars parked in the car park and reject any cars that are unregistered or unroadworthy. You might even consider a “surrender tackle” contact with the local council to get them to tell uyou visitor parking is for bona fide visitors.
All you are doing is storing up problems for the future and giving some owners free parking at everyone else’s expense.