I think the OP's need a better understanding of their TV's "capacities". Payload will be reached or exceeded before tow capacity. I looked up the brochure
specs on this TT and the dry hitch weight is listed at 600 lbs, but even if true, I'm not sure why the OP would be using dry hitch weight to determine capacities.
Unless you are planning an weighing every item you bring aboard, there is no way you can say "We don't plan on ever putting more than x,xxx lbs in it".
If you are calculating weights, you multiply gross TT weight by 13%, so in this case 7750 * 13% = 1007.5. Add in appx 100 lbs for WDH and then the weight of everything else you plan on putting in the truck, then subtract from your payload number. Keep in mind that the factory number is decreased by accessories put on after the fact like step bars.
If you want to take the guess work out of it, then load up the truck as you would for camping - including a full tank of gas and get it weighed - Google CAT scale locator to find one near you.
Pulling a high walled trailer down the road in an overloaded TV, you will come to realize that it's not fun, and you won't want to go far. Tow capacity is determined at the manufacturer by towing a flat trailer with weights and a 150 lb driver.
Since calculating weights is not giving you a big cushion to be worry free, I strongly suggest getting your TT's actual scale weight. Good luck.