Buy a Superjet
I just emailed my local state farm agent. All I said was I have a WDK jetski registered as homemade with a state-issued HIN. He said they do not do policies for "custom trick jetskis"
You are one of the only people I've heard of getting more than just liability on an am hull besides when wake zone was a thing.
Call the guy I posted the link to. My bob and my reaper are registered as home made. He has also insured rickters and many others.