First I have seen of this thread. Just a couple of points to consider;
Sandman only is impossible, there is no way of proving if some cars are Sandmans or not and you can imagine the possible legal implications of this when it comes to an insurance claim.
I really think you will struggle with committee numbers in all states. It's a fairly small target group. You really need to open it up to Sandman owners and welcoming all owners of Holdens of whatever series the committee votes on.