You'll be purposefully overloading the hitch assembly. Tongue weight for an 8k trailer should be 560-800lbs (7-10%). That's between 12% and 60% overloaded. You're putting a lot of faith in the engineers safety factor calculations.
Like a purposefully overloaded hitch, and a panic stop?
Not trying to be a dick here, but it appears like you're taking a shortcut, and I'm really unsure why.
@haknslash has a proven solution that works. It's neither cost nor time prohibitive. Do you really want to roll the dice with your new boat that you spent thousands of dollars on, and your family in the truck with you, to save a couple hundred bucks and a Saturday afternoon?