The weights you posted are dry weights . There is no industry standard to determine a dry weight. When you add your optional equipment and the trailer is ready to be shipped it should be weighed by the mfg. and a label installed. That way you know , if it becomes overloaded , it was you ( the owner ) that did it by adding too much personal stuff .
I own a Jay Flight 23RB . Judging by my real weight rolling down the road (being extremely lightly packed) , IMO, your TT will be close to that GVWR of 6000# with a hitch weight of approx. 700#, as mine is.
1500 as a hauler ...I understand trying to have a less expensive truck doing the job to tow and also have a truck that rides nice while not towing.
A 1500 will do the job towing 6000 lbs but you have go to a scale and have it all weighed and learn how to properly weigh a TT combo.
IM not an engineer or any kind of expert. Im basing what I say on my years experience towing. Driving down the road in a straight line with no events might not be the same as tying to control a maxed out rig during an emergency maneuver. A 1500 has a softer suspension than a 2500. The more heavy 2500 might offer the operator a wider window of time to regain control operating a near maxed out rig.
Test drive both 1500 and 2500 trucks and see how the empty ride feels to you. Then decide. You can always lighten your load but with a 2500 you won't have to give it thought.