If you go to the reservations site and fill in the info, it will then tell you if there are sites available for your approximate time period. It will also show you if some of the sites are available for "walk in". Most have some sites set aside for those that just drive in. You can also fill in the length of your RV and when the choices pop up the size of the sites show. Some have photos of the site if you click on the site #. You can actually research alot about the park by starting the reservation process, just don't complete it with a payment.
That said --- the government shut down is closing the COE parks. We are in one now and have to leave by tomorrow at 8pm. Sure alters our travel plans and expense.
You can also set up on a "reservable" site that is empty and pay for 3 days and then move if someone does reserve it. There is a 3 day window on reservations meaning if I reserve on Monday - I can't get the site until at least Thursday. If you want to stay longer, you may just need to change sites.
