@ScottHarr_JT Thanks for bringing this topic to the forum. @JTRUBI is correct, the trail rail system will need to be removed prior to installing your GFC for a few reasons. The most notable issue is the lowered positioning of the rail and how our mounting system is engineered to keep your camper secure when blazing trail. Because of this distance, we must mount to directly to the truck bed rails for proper fitment.
We also noticed an issue with the rails after a dealership lines the bed with either Rhino Liner or Line-X. Due to the liner thickness, the trail rail is often loose and had many stripped screws (classic).
Once the camper is atop your truck the rails can be re-installed, but you may need to make minor adjustments to account for our mount placement. Hope this helps! 