Wy don't you have an 'affiliated membership' as per Commodore Car Club of WA?
In this, any non Commodore is allowed to join, however for track events where they compete against others, the affiliated members aren't allowed to join in?
The affiliated members pay less, since they are less 'active' however still get to join in on cruises and the like
I think the main core of members should be Skylines, and the rest as an affiliated membership where they are less proactive, as described above