I put a 20K Reese in mine and pull an 18,5 K fifth wheel with no problems. I have a short box but my trl is curved on the front so I have no clearance problems. I considered a slider hitch but they are pricey. My rails in the bed are bolted in side to side. I saw one the other day that although not a slider, the fifth wheel hitch could be unpinned and moved back a foot or so. That could be handy and a real tight uneven keel place but I try to stay away from that kind of stuff.