Towing with a minivan

Weight concerns have already been addressed so I won't go there. What I'd like to bring up is how miserable you will be, in the truck lane, doing 35-40 mph, peddle to the floor, while everyone else is doing 70, just to get to the other side of that mountain. You won't have little hecklers complaining about how everyone is passing you, including motorized wheel chairs, like we did. But it still is not going to be fun.
I second the transmission cooler suggestion. Some mini-vans don't have external coolers. My son's Honda mini-van didn't have one. He didn't notice it until he was in getting his transmission replaced. They suggested getting one.