It looks like you vehicle may tow around 9,000lbs (quick search so I'm not 100%) then you want to deduct about 10-15% of that, so 10% would be about 8,100lbs. If it were me I wouldn't go over that amount and that means the camper is fully loaded with fresh water, all your food, clothes, pots and pans, etc...
I have a 2010 Ram 1500 that can tow 8500lbs and we have a 2011 Passport Ultra Lite Grand Touring 29' and fully loaded it is 7200lbs so I am close to my limit as well and I can tell that it's a little on the heavy side (that's why I'm getting a Ram 2500 next year)
The Keystone you have listed, I took a quick look at, and it says it's 7,800lbs dry (nothing in it) so that only leaves you with about 300 lbs of stuff which you won't be able to do. I didn't look at the others though.
We also have 5 kids and 2 adults and ours sleeps everyone just fine.
This is just to get you pointed in the right direction. I would definitely look up your exact vehicle's towing capacity just to make sure.
good luck!
