MAX PSI/Max Load Ratings is based on COLD Inflation...not driven on for 2 hours
Increase in PSI is already incorporated in Max PSI/Max Load Ratings
Check/Adjust tire pressures in AM prior to travel.
Leave it alone during travels --- check/adjust again next travel day
What is the weight on your trailer axles?
Where do you get that 8200# 5vr number?
What are 5vr axle ratings...5200#, 6000# etc?
What is the max load rating on those tires?
80# (Max PSI) would be needed IF---IF weight on tires was at/near Max Load Rating