Add up what your family weighs and subtract that from the 1390 lbs. Now subtract the 660 lbs that the tongue weighs from that. Now subtract another 100 lbs for the WDH. Thats what you have left for tongue weight items like a battery (50lbs), propane (40 lbs) and any gear that will go in the truck or in front of the TT axles. Lets say 200 lbs. Just for speculation purposes it looks like you would have a TW of around 950 lbs.
1390
-950
=440lbs. So you have in theory less than 440lbs for family and all the stuff that won't fit in the TT that will go in the truck. Looks too close for me.