There is plenty of campsites on the dirt roads that are up in the mountains out side Marysvale. I've seen a lot of hunters that pull there rigs up to 10,000'. The trail is a 232 mile loop and you can drop down into towns to gas up. Myself I would go up Beaver Creek RD out of Marysvale it tee's into the Paiute Trail, turn right the first right is the Deer Creek trail drops down to Hoover's and Hwy 89. Go on to the next right and it drops into a large flat area has a firepit and about a 1/2 acre in size. Unload your atv and do some recon. Go on line and order the National Geographic Paiute atv trail map #708 you can spent 5 days there. I think this spot is about 9,000'
We've been riding trails in Utah for the last 5 years, we are in Kanab now after spending 3 weeks in Bryce Canyon, Marysvale and Sterling dry camping at all locations.