Recommend Tire Pressure

You are absolutely welcome to your own opinion but I will stick with what the real experts recommend, that being the tire and vehicle makers and not someone on the Internet likely with no real engineering credentials at all.

Here is a quote from Goodyear RV tire website; goodyear.com
Goodyear Tire and Rubber .... weighing RVs
Special Considerations

'Unless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up."

And from Carlisle ST tire warranty pages; http://www.carlisletransportationproducts.com/product/tires/trailers-toy-haulers-towables/radial-trail-rhcarlisle.com
-Maintain air pressure at the maximum PSI recommended on the tire sidewall.
and
"The Warranty is void if the tire or wheel fails due to damage from improper inflation pressures, exceeding the maximum speed limit, or overloading the tire beyond the maximum load capacity stated on the sidewall.

Vehicle experts ?? I assume your thinking RV trailer builders are some kind of experts on tire design or assume they can or will choose the best tire for their trailering customers.
IMO trailer mfg haven't proven to be the best source for tire choices/tech recommendations.