Mine is mounted on a Harbor Freight trailer.
I cut a section of oak lumber, ~1.5″ high and the length and width of the bunks. I epoxied it to the bunks to provide clearance above the fenders. It worked out just fine. There’s a bit of space above the fenders and it doesn’t interfere with entering or exiting the camper.
I followed the manual and installed the camper’s rear end 32″ from the axle. It is rather light on the tongue, but an added footlocker loaded with gear and spare tire have made the tongue notably heavier. I also bolted a pair of stabilizer jacks onto the the trailer’s rear end to keep the camper from going tango uniform.