I'm not an Elk, no desire to join their organization either. But a quick internet search landed me on their web site immediately. They sound like they are a good organization with some really good ideas. But it also looks like you can not just decide to join at whim. You have to be recommended (have 2 sponsors) to join (basically, you are "invited" to join). I know some folks in the Masonic Lodge, and theirs is the same way, you have to be recommended by someone from a local lodge.
Here's a link to their membership requirements:
click here.It looks like their campgrounds are locally owned. In order to make reservations you need to contact each facility. This page give a list of their campgrounds. Although the length of their spots are not listed, you'll probably have to call each one you're interested in to find out the specifics of their local facilities.
Click here for Campground Info.As with any club, you'll probably have a financial responsibility to help support your local club. Shoot... you can't even become a member of a local church without being expected to pledge 10% of your income! That's usually in the membership commitments.