I ran 19.5 tires and wheels on my one ton and carried a couple hundred more dry pounds than you on airbags at 15 psi on a one ton. I truly loved the fact my tires and wheels were only at 80 %. Running right on max, and you are underestimating your camping load, is running too close to the wire for me.
But I know many others carried their rigs on beefed up 3/4 ton trucks like mine and they managed.
Driving the new fifth wheel is so much scarier than the camper ever was. Going downhill, instead of carrying 5000 pounds and relying on my brakes and transmission, I have to rely on my transmission alone to slow 9000 pounds, and I have to use the brakes only in emergency. Riding the brake will prove to be a disaster if I ever go past what the engine will hold.
So, beef it up, and enjoy the new rig. Time will tell you to keep it or upgrade.