The OP did say in travel trim...which is the correct way to conduct this test.
A family of 4 can easily push 600lb. 300lb firewood. 120lb generator. 150lb bikes. 100lb running boards, 200lb fiberglass cap....that's pretty close to 1500lb in the truck before hitching up (the exact makeup might vary but not unheard of numbers).
The only questionable part is going from #1 to #2, the truck axles go from 7500 to 7920 which implies a 420lb hitch weight on a total trailer weight of 5040lb or about 8% hitch weight. Not unbelievable but marginal for good towing.
I would look at shifting more weight to the front in the trailer to get that percentage up.