80 psi in a 110 psi rated tire isn't the best idea nor is psi recommendations from a minimum pressure chart the best idea either. Were talking tires on a trailer tech...not tire on a tow vehicle tech.
For 7k-8k axles I would use max sidewall pressures for best long term service.
If you have 5.2k-6k axles then I like what these folks have to say on the subject;
rvsafety.com
Tire Load and Inflation Ratings
Note: Towable – Travel Trailer/ 5th Wheel owners Due to the severe use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.