Stay with cold temp inflation numbers and adjust you pressures as necessary during the year as local temperatures change or as you move around the country. I'm also an 80 PSI owner which gives me slightly more capacity in the tires than I have in the axles. Pressure increases can be high as air and road surface temps increase but those numbers are factored in by the tire builders. You have to consider that regardless of if the coach is rolling down the road or parked in the driveway put to bed for the winter your tires need to be aired up to the recommended pressure for the load we demand they carry. Bleed down a high daytime temp and you could be under inflated at 5AM the next morning.
I have my weight checked twice a year. In the spring after taking out all the stuff I didn't use all last year and loading new stuff I probably won't touch all season. Also at the start of our two weeks on the road mid summer when I'm really loaded with stuff I think I might need or use but never do. The hard part is figuring in the weight of the rocks my Navigator collects along the way and forgetting to take them out of the coach when we get home before the next trip and more rock collecting. Maybe I should go with 85 or 90 PSI just to be on the safe side?