Try Lizzy and Charlie's R.V. Park in Marysvale. They are very ATV friendly and just all around extremely friendly. Great trail access a small market and restaurant. I have never stayed at Big Rock Candy Mountain before but the campground looks nice and is close to the river. As I remember the main trail up from Big Rock is basically an ATV trail called Dear Creek Run and I don't know if they allow Razors on that trail. Their restaurant there has great food with goooood Rib Eye Steaks. Another place you may consider is The KOA campground in Richfield (about a half hour by vehicle on the highway from Marysvale). They have new owners now and are ATV friendly. Richfield has all the things you would expect, Walmart, KMart, Pizza Hut and a motorcycle dealer / repair shop with reasonable rates. Many of the main trails are accessable from Richfield some with a small drive involved on the UTV but the town is ATV/UTV friendly as is all the other towns in the area(you don't have to be street legal just safe, courteous and sane). Sorry if I sound like the Chamber of Commerce but I love riding up there!
Check out utahatvtrails.com or atvutah.com for more information.

Goldfinger