My co-worker just returned from a trip to Big Pine CA for some early season trout fishing. Lost a tire on the SRW Superduty with camper on it. Luckily he felt it as soon as it started to de-laminate, and before the tread started flapping he had it off the road.
Truck campers are much higher off the axle than a motorhome, and usually very heavy in the rear so unless a you have a DRW truck, more tire on a SRW is better than trying to cheap out or play the % of safety margin game. An engineered margin is only as good as the manufacturer was that day. Tolerance is always noted, but on a heavy truck with highly mounted mass like a camper pitching, yawing and rolling down the road I don't want to be wondering if my tires were at the bottom of tolerances or the top! Go big as you can or go DRW.