Ok, hitch weight. Take that Keystone you mentioned, at 875 lb dry hitch weight. The TT is over 32' long. Ever play on the teeter-totter? Recall that the farther out from the fulcrum you sat, the more your weight affected things? Think of your TT as a BIG teeter-totter. To the near end you are adding 2 full LP tanks and a battery. And don't forget your weight-distribution hitch, an absolute must-have for such a long TT; add nearly 100 lbs for this item directly on your receiver. Then you're going to load your clothes and other gear. Think about where... will it be in front, or in the middle, or in back? And your water, where is the fresh water tank? If it's up front, a full tank of water could add a couple hundred lbs to your hitch. Then you're probably loading passengers and gear in the back of your TV, which adds to the rear suspension load. Do some figuring. Every situation is different.
At least the Grand Design is only 575 lbs dry hitch, according to what I looked up. That might be to your advantage. Even so, run the numbers and see if it will really work. You do want some cushion; don't push your luck.
Definitely make sure you get some LT tires, preferably a bit lower profile than OEM, to reduce tire squirm and aid handling.
If it were me, I'd buy a hybrid to sleep the brood. Something in the 23'-25' range. But then, my trailer doesn't even have a tv; I find the outdoors and the scenery plenty entertaining, along with a good book or two to read. Ahhhh... peace and quiet, no "talking heads", and I get to create my own action/adventure. ;)
