There is a couple of lower sites at council that you could get that size trailer in but the rest are just camper and tent sites. The lower sites fill up soon and you get all the dust from people coming and going. There is another site in the area that might be worth a shot, PM me for details.
Dont know how we missed you up there Saturday. We staged at the bottom of the #2 and rode Trail #2 to the Boundary trail and then to #259 and rode the lower section(3 miles or so) of #259 from South to North and then doubled back at the Rock switchback, that was fun. We Ran into a couple guys at Dark Meadow on a KTM and Yamaha. Saw no other riders.
Have fun up there. Best riding in this part of the State, IMHO.