Most of the Premium sites will probably fit your rig and some of the Preferred/Full. Regardless, the Fort will take some huge RVs somewhere. The key is specifying how long and/or wide your trailer is on your reservation. The CMs take that into consideration when assigning sites.
The bigger issue with some of the Preferred and Full loops is getting through the loop and backed into your site. I towed 44 and 48 ft trailers with my race team. You need a lot of room on the street to maneuver into a spot. Trees, trash bins, other cars and sometimes just the angle of the road and site make the longer rigs tough to park. Premium loops/sites generally have more room to get around.
j