I wrote:
For proper balancing, you need 12-15% of the trailer's total weight on the tongue. So assuming the trailer will weigh 6500# when loaded, you'll have 780-975# of tongue weight. Let's call it 900#. Figure another 100# for the hitch itself. That leaves you with about #150 for people and gear.
This is less than ideal. If you have only one passenger, you might be OK, but move everything you can out of the truck and into the trailer.
The above numbers assume proper weight distribution. It's not just about getting all the weight you can off the truck, it's about proper load balancing. If the (weight-distributed) tongue weight is too light, the trailer will sway.
If you were to put 3000# in the rear-end of the trailer it would greatly reduce tongue weight. But I sure wouldn't want to be anywhere nearby when you tow it down the road.
-- Rob