Towing with a van conversion

We'll See wrote:
Your bigger concern would be slippery launch ramps. That is why 4 wheel drive or awd is preferred launching boats.

A van has a lot more weight on the rear than a pickup truck.

I used to tow 6500 lb with a high top conversion with all the bells and whistles. The deluxe conversion used up most of the payload, unfortunately, which led to me towing overweight, which eventually led to a cooked transmission.

Pulling an 18 foot boat should be no problem.