You Need to leave at least 5PSI in the bags at ALL times, even that psi is going to raise the vehicle .50-.75
Now that being said I would MAX my PSI at 20PSI. No way in Heck are those cam Bushing going to support the increase Pressure. WHY do 1/2 ton owners believe they have a pulling TRUCK is beyond Me?..... wait until you need to have emergency STOP or Some Young Kid runs out in front of you or you need to take evasive action.... BUY a truck that exceeds the the ground pressure X2 , So If camper GVW (Loaded is 7000LBS) buy a truck that's rated to pull at lease 14,000LBS. YOU always need More Iron then the wagon your pulling.
I strongly recommend a LT tire, I checked your LR Index is 113 2535LBS with those Nexens, Its still a P Rated tire.
I only do HAZMAT crashes, although at Times I fill in for Vehicle crashes ( can't recall responding to and accident, accidents are unavoidable) Its rare I don't find the power to be sufficient for the wagon its pulling, when/if a crash is Investigated ( 1/2 ton Trucks) , If theirs a fatality Micro wrenches will be used to check everything. The ground pressure will be checked and if any of your tires exceed the State or FMC allowed ratings it gets ugly from their, Wagon/Power.
Everyone's skill level will be different and I certainly don't know yours's uga40, Just adjust Your thinking and drive safe speeds and you'll probably be just fine.