I've had very bad luck with tires on my dually due to separation issues. I'm only getting 15k to 20k before this happens and 3.5 to 4 years. I only have the camper on the truck about 3500 miles a year...
We've had BFG T/A Radials on my PU for years - 285-E - and never had a problem with weight. We keep them at 75-80 psi rear, 65-70 front. Been using them on our construction trucks (three) for just as long until we retired.
Been camping-RV'ing with Truck Camper since 2002 - Lance 845 on its back. Truck is HD2500 SB - 6.1L w/410 RE ... Hope that helps. Just one opinion. M44