You didn't offer very much info. How big is the boat? Why do you feel the mini-van might meet your needs?
I drag a 17-foot Boston Whaler Montauk around behind a Ford Explorer Sport-Trac (used to tow it behind a Ford F250 Super Duty Power Stroke ) Its the melding of an SUV and a Pickup Truck....4X4; tows 3500lbs out of the showroom; plenty of interior room (5 adults), bed handles 8 bales of hay for our 2 horses; tows the horses and their trailer easily as well able to tow the Montauk (fully loaded) up a MONSTER hill here in Gig Harbor without blinking an eye. Wife loves driving it and, if we had kids, we'd have no problem dragging them around either (unless we were trying to repopulate the planet with more than 4.) Unless you've got a boat >3500lbs and 6 kids, you may find some better options out there besides a mini-van.