I'll admit I don't know the first thing about tow in surfing but I would assume it fits under the same marine laws as waterskiing, thus you require a minimum 3 person ski to do it. One driver, 1 x Observer and capacity to carry the Skier (or surfer) if they are injured.
Also skiing behind any sort of jet regardless of the power is a poor second to a proper ski boat/wake boat, which you can buy for the same kind of money. I got out of my Jetski years ago and bought a half share in a decent ski boat and it's much more sociable. Friends and family can join in etc.