Always 80 lbs psi in 'E' tires, or go by GVWR?

[Audionut]

On our newly purchased used 2015 KEYSTONE COUGAR 30RLI with ST225/75R15D china bomb original tires on 15x6 wheels, we run them at max recommended 65 lbs psi.

It is overdue for new tires and I’m thinking of going up to a E rated tire due to it is a 36’ TT, 2 axle, dry wt is 7720, and GVWR is 9500lbs.

So when you go up from a D tire with max 65 lbs psi, to an E tire with max 80 lbs psi I was thinking you should run them at the recommended max of 80lbs, however I just spoke with a tire dealer who said to not necessarily run 80lbs. It depends on your GVWR. So do you all agree with that or would you just run 80lbs in them?

And one thing I need to do is weigh my rig to see what our total weight is when it is loaded, but I find it hard to imagine we could be over the GVWR loading it up with just normal living stuff.