stop by home depot and grab some bags of gravel. they will seriously add some weight to the rear of your truck. hopefully he wont b*tch about you not running it in "stock" form.
if youre seriously teetering on this decision and have a good amount of money to lose then maybe consider renting the same vehicle and doing a secret test run before-hand. or finding someone with the same vehicle and paying them to do a trial run with you. all the theorizing in the world wont help you like the real thing. sounds like a risky bet

ps just out of curiosity...
we dont have these kinda hillbilly activities out in these parts so im curious if this can f*ck up something on the trucks?