You can get a great reference book on starting an OHV/ORV park from the National OHV Conservation Council. It's a great guide and will answer all your questions and give you some great ideas on insurance, bonds, design, public involvement, signage, etc.
www.nohvcc.org
In a recent issue of BlueRibbon magazine, KansasROCKS (OHV Park) owner David Killion did a great write up of how he started his park, what he went thru and how he got his permits and even some grant funding (RTP funds).
Del