My situation is halfway similar- 3 Suburbans over the last 15 years: 1/2 ton with 3.42 & 4 speed, 1/2 ton with 4.10 and 4 speed and 3/4 ton with 3.73 and 6 speed & a 27 ft bunkhouse, 7000 lbs gross.
I think 1) you are near the maximum capacity, and 2) are probably OK.
After reading 10-zillion "can I tow this threads", my take away is that having a little extra truck makes for more comfort.
Our 3/4 ton seems a bit more stable, and the point that folks make is that the axles, springs and brakes are designed for more weight. But both previous 1/2 ton Suburbans pulled ok (and the difference in the 3.42 vs. the 4.10 was pretty minor (heck, the 6-speed spends LOTS of time with the engine wound up to pretty much similar, if not higher, RPMs)).
There is probably a safety advantage to going bigger, but conversely, it's very wrong to be towing at 80% of maximum and feeling smug! (because you have a 3/4 ton or 1 ton or dually, yada yada yada). Towing anything heavy and big requires good attention and good driving hobbits regardless of the TV!
If I towed LOTS and LOTS, I think the "80%" rule is probably more important. But if you are like so many of us and the towing is more intermittent, your weight and truck seem to work- again, with the disclaimer that you are probably maxed out (and that pulling and accelerating are not the issue, but stopping and dealing with wind).