I can give you some of my first hand experience with towing over your GVWR.
We have a 31' Shamrock 21SSL. Hydrid with a 8' exposed deck on the front for toys.
GVWR of 7335lb, Dry of 5143lb, dry tongue of 335lb.
Tongue weight is quite low due to the front deck not being loaded with cargo.
Tow vehicle as per my sig (Air bags, E-Rated tires, 3.92)
I've taken this trailer out on two trips, both to the rockies of Alberta (Canada). Each time I have not loaded the front deck with anything.
One trip through Crowsnest Past with 3 occupants, here's the numbers:
F- 3703lb
R-3460lb
Tr - 5664 lb
Another trip to Waiprus (foothills), here's the numbers:
F- 3593lb
R-3086lb
Tr-5356lb
As you can see I don't quite have the distribution hitch set up quite correctly. It's set properly in order to maintain trailer levelness. I've just been playing around with the number of chain links when hooking up the WDH bars.
As far as truck performance. I've had zero concerns with acceleration or braking. Going up 7% grades is not an issue (other than fuel gauge move to "E"). Going down 7-9% grades is no problem using a combination of tow/haul and engine braking. I try not to use my brakes as much as possible.
The only issue I've really been concerned about is tire traction. I'm still trying to dial in my WDH settings, and it seems like each trip has a little bit different variables. On the last trip I did stop on the side of the road to make an adjustment and it made quite a big difference. I was experiencing "porpoising", I had too much weight transferring from the rear to front (chains too tight). Loosened up 1 link, improvement. I probably could've gone another link.
As for my towing experience, I wouldn't consider myself a newb, but have never really paid attention before (Dad would just tell me to take it). I was nervous for our first trip out into the mountains; had never towed with this truck or with this trailer. The first 20 min were pretty quiet and focused, but after that it was business as usual.
Just remember to check, re-check and then check again. Also, if friends help you get hooked up, make sure to check everything that they do. I sometimes would almost prefer to have no help, that way I only have myself to blame.