Re: membership campgrounds
Generally, a 'membership campground' is a network of campgrounds. You 'buy' a 'timeshare' which allows you to use your 'home' campgound and other campgrounds in the network on a specified schedule or more often, for specified lengths of time and number of times per time period.
If it has campgrounds situated where you want to be, at the times you want to be there, it can be a good deal. However, you will pay a hefty fee to sign up, and a monthly fee every month until you sell the membership, often at a significant loss. Plus some of them have questionable practices, like signing up people and then dropping most of the campgrounds. Same fee, much less chance to use it...
You can buy the membership of someone who decides it is not worth it usually at a significant discount, but then you have to pay the monthly fee until you sell it.
Good Sams/Passport America/AAA/AARP etc is often a much safer (and cheaper) way to go. These all pay for themselves as opposed to the membership which often does not.