What is most important to you ... price, on-site amenities or access to the trails from your campground ? I like Indian Ridge, Pinnacle Creek and Pocahontas trails which are all interconnected.
I've stayed at Ashland Resort and it provides direct access to the trails. It's a white knuckle drive on the narrow road to get to the campground from US-52, but it is pretty nice as ATV campgrounds go. Expensive though and only real amenities are gas, laundry and showers available on-site.
I've stayed at Twin Hollow Campground in Gilbert. Up on top of a mountain, peaceful and very nice people running it. Not a pleasant trip up the long access road (driveway) with loose rocks. This has direct access to Rockhouse trails. No amenities to speak of.
Can't help with rentals.