There are a lot of hidden weight adders to a truck, like oversized tires, tube steps, bed cap or cover, etc etc. 400 lbs over the spec'd weight is not a lot.
So by now you should have the gist that this trailer is a little over what your max ratings are...but honestly I wouldn't stress too much about it. We towed a 34' TT with out 2500 Suburban, the GVWR on the truck was 8600 lbs and it was at least that when we loaded up to go camping, sometimes 8800+ if we had kids' friends in the 3rd row + firewood in the back.
Before you get too caught up in the numbers, think about your options...
Option A is you buy this trailer, load it up, dial in the hitch, then take the rig to the scales and see where you are. My guesstimate is that you will be a few hundred lbs overweight on the truck, it will drive OK but it will work pulling that trailer. You may have to make some mods to the truck like a trans temp gauge, external cooler, possible airbags or spring helpers in the back, and managing weight and what you pack will be part of every trip. You may or may not want a bigger truck down the road depending on how happy you are with how it drives. Plan on taking most hills at 55mph or under.
If you're not up for that and just want to hitch 'n' go and not have to worry about any of that, then option B is to just buy a smaller trailer.
The challenge with Option A is that there are no guarantees, you can invest $$ in truck upgrades and still not get to where you want to be. We went down that path, as did many other members here, only to wind up with a bigger truck, and in our case, followed by a bigger trailer.
You need to stay under the axle capacities, because those ratings are safety-based and tied to brake and tire ratings. GVWR is a rating set by Ram to ensure component longevity and a good driving experience. You can load past GVWR but the truck won't drive the same and stuff will wear out faster.
You're not going to be wildly overloaded to say that this TT is a non-starter for you, but you'll always be right at or a little over the trucks' ratings, and know what that means going in.
