"hauling different" are you referring to tow capacity or vehicle weight capacity?
You can tow a lot more than you can set on the rear axle--the only way to know where you stand on rear axle weight is to weigh the truck set up for towing and find out what is already on the rear axle--then add the 2500+ lbs for the pin weight. I believe you will be over by quite a lot, and even more when you weigh the trailer and find out the pin weight as it sits ready to camp.
You are correct--not much difference between 2500HD and 3500 HD SRWs towing capacity. But the 3500 should have about 1000 lbs more axle capacity than the 2500.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired