There are a couple of web sites you can post on to let folks know you are there. They are pretty well known amongst traveling trail riders. Horse & Mule Trail Guide USA: Trails, Campgrounds, Overnight in Missouri Horseback Trails and Campgrounds - Horse Trail Riding and Camping
I don't know if they charge to post an ad, but I think it would be worth it.
Check to see if there is a trail riding club in your area. Those folks can be very helpful even if you don't own a horse.
Good luck, hope everything works out
Oops I just noticed I put up Missouri, you can just click on Min on the page to get to your state