Check out Fishweb.com, Mi-Trale, or VVmapping.
Fishweb will have links to lodging, and campgrounds.
I just bought a new Can-Am Maverick Xrs 1000 and will be looking around the St.Ignace area and North to do some riding as well.
If you find a good place that have trails for ATV/UTV post it back on here.
Good luck in your search.