Does anyone have experience pulling a fifth wheel with a longbed and an over-the-rail toolbox? Should this be a concern? We currently have an under-the-rail toolbox but DH wants an over-the-rail style. Appreciate any input.

I did for 1 trip with my old truck and trailer.Got home and sold it and got under rail style.Mine blocked my vision to much when hooking up and I couldn't keep track of what was going on in the bed when towing.They do make low profile style that might work if you really want one.

If your concern is hitting the box with the 5th wheel in a sharp turn (near 90 degree), you won't under most circumstances. I'm sure there is a possiblity if the truck is off camber and the 5th wheel is off camber as you turn you may hit the box. This would only happen in extreme manuevering, like trying to park in a tight, very unlevel spot. during normal driving and turns, there's no chance the two would hit. I had built a dog box that stuck up 1 3/4" inches above the rail in my old truck. I made it big. It went from side to side (outside of p/u bed) and from the cab to very close to the hitch. I never hit the box, however I did dent both sides of the cab with the trailer when manuevering into unlevel spots requiring a tight turn. On the 5th wheel I had the axles flipped at the factory so I had lots of clearance between the pickup bed rail and the bottom of the 5th wheel (about 8 inches). The truck was a 4X4 with a 3 inch lift kit. On my current truck I have a flush mount tool box and it works great.