This guy rents out space at his ranch... you'll have to ship your own tents there in advance to have shelter to sleep under.

Damon NOLAN's Bluff Creek Ranch
537 Owl Creek Road
Box 110
Warda, Texas, 78960
United States
bcrdamon@yahoo.com

I didn't bother registering for MS150. I'm going up self-supported a day early, then going to help at my team's finish line tent.