Um answered ya on the other forum, but we used  http://www.hobbyhorseovernightstables.com/  and appreciated the roofed shed with runs, easy on off of I90.

I have also stayed here and it is very suitable. If you are worried about cost you can stay at Cabelas free of chrage on a first come first serve basis in the portable corral panels at Mitchel

I stayed at Hobby horse last summer, very nice horse set up.  It's not cheep but very secure and clean you park inside a locked fenced in area within walking distance to restaraunts, I think it was $20 per horse and 5 or $10 for the trailer - no hook up  but you get a free hat.  I then went over to the Flying J truck stop for a really nice shower that was $7.00.