Until someone shows up with a real number, here's an estimate (ignore dry weight numbers, they're for suckers):
The FR website shows UVW is 5170 lbs and the CCC is 1524 lbs. That means the GVWR will be about 5170 + 1524 = 6694 lbs. (This is close to my 2503S's GVWR of 6538 lbs.) Tongue weight usually runs 12-15%. If you assume the lower 12%, that's 803 lbs, but could be a bit more. Assuming you have a WD hitch (and you SHOULD), that's another 75-100 lbs, so I'd bet your tongue weight will be close to 878 lbs, maybe a bit more.
Look on the drivers door frame of your Grand Cherokee and see what it says for your payload limit. The payload number has to include the 878 lbs hitch weight above, PLUS anything you put in the truck: you, wife, kids, dogs, stuff, etc.
If you're looking at actual trailers, look at the white sticker on the drivers side of the trailer. It will tell you the actual GVWR of the trailer you're looking at. Here's mine: