Informal rally at Hawn SP just 15 miles west of St. Genevieve, Missouri on Friday March 30 - Sunday April 1, 2007 (they don't turn "on" the shower house water until April 1...so you can "boondock" w/ electric until then.)
Beautiful park, great hiking trails...I think there are only eight reservable sites in the first loop for the March 30 - April 1 weekend. There are other FCFS (first come - first serve) sites in the lower loop near the playground and shower house.
For reservations
Missouri State Parks and Historic Sites, PM me if you are thinking about going.