Not an unusual policy, see it at a lot of CG's. Especially on the "big weekends" where they require a 3 day reservation. Too many people pre-book, then cancel leaving the CG with an empty site that would have made money. Would it be nice if they refunded the majority of the deposit if they manage to book the site? Yes, it would. However, they have no obligation to do so... you knew the policy when you booked.
Maybe you can rent a truck (Home Depot--$19.99 a day). Spending a few extra to enjoy a weekend camping, beats losing it all and sitting at home.