I am looking to get a group together in late April for a ATV/Dirt Bike ride (sorry no trucks are allowed at the area we are looking at) Rates seem very reasonable. $5 per vehicle per day and I believe it's $13 a day per camp site. Which that I will confirm with MDC when I can get ahold of them.
This is the area we are looking at, Finger Lakes State Park | Missouri State Parks
They have a motocross track as well if that interests you, I wont be using that, I just want to ride the trails.
Post here if your interestred and I will keep this updated.
FYI, Tentatively we are looking at April 19-22