I agree, i have only been a member for a handful of months with very minimal posts. I would still want to have the privilege of being able to buy and sell an item when i want/need too, hence putting the 3months/number of posts out the window effectively.
And if people don't want others knowing about a cruise "Police" then why post in a public forum? Call a few of your mates that you have met on one of the public cruises and i'm sure they will be more than willing to go for a nice drive with you.
Alternatively there could be a section for paying members which is exclusive and can't be seen by any other pubilc or non paying members. Who knows this could already be in place as i have not got a paid membership yet (still waiting for my car)
my 2c