IRRC from a previous post somewhere, I believe MA is like WA state, you need to buy tonnage for your pick up. Just make sure you have proper paid for gvw, ie higher than you actually wieght!
Other issue I don't know, not mentioned, you state RAWR is 6340 lbs. What is limiting factor? If it's the tires, there is nothing illegal or wrong about upsizing them when you need new ones to gain payload capacity, closer to you axle or spring capacity. Your door sticker won't be correct, at least where I am, LEO/CVEO's don't go by door sticker rating for how much I can weight. It's paid for registration.
I don't see any issues with what you want to tow. Be it true or civil legal issues.
Marty