Nice setup though!
AF 811/860 is my fave camper. Big camper features and short bed ready!
If it helps your peace of mind, I hauled our AF860 all over the country on cheapo weak, squishy sidewall, 5-6 year old OE takeoff Firestones. Without issue. Running 75mph + consistently on the open road.
I’d trade a brand new set of those tires for your old 19.5s, today, and be even more confident!
As long as they aren’t dry rotted.
Note, you can’t see some dry rot on fully inflated tires.
Try this. Deflate one of the tires on the truck until almost flat and see if there’s any cracking in the bottom part where the tire is flexed. If not, good to go.