Efoil Laws?

[jayhawk_nation]

I was cruising around earlier this week on some new efoils, and the marine patrol came over and pulled us over! Turns out, you need registration stuck on the front of your efoil like every other boat. It didn't occur to me that this was necessary. Seems a little over the top. Less than 5 feet and 5 horsepower boat?
Not sure if we were the only ones who didn't know this.