It's funny you should mention that, as I was just doing that math. The kiddo is only six, but even adding in weight for her to grow into an adult, if I add that to me, my wife, one German Shepherd Dog, the tongue weight of the trailer, and 400 lbs of personal gear stowed in the truck bed, I still come in a few hundred under max payload for the truck.
We started out as backpackers, so we travel pretty light. The new trailer is only 20' long, but it feels like a goddamn palace compared to what we are used to.
Hell, we could kill an elk, quarter it out and still be under weight I think.
I had to redo those numbers a couple times to make sure I wasn't missing anything.
I guess 20 years of technology really does make a difference.