Airboat insurance

Geico Marine. They require a full cage (pictures required) and airboat experience (your word). They will insure for an agreed value and you pay accordingly.
Who ever will take you !

Markel / Charter Great Lakes another option.

Some only do factory boats

Some only do automotive power

Most want full cages now to keep people away from exhaust pipes and belts.
I was notified by Geico over the weekend they are not renewing coverage on my Airboat and they no longer offer coverage on Airboats, I believe Bates Insurance in Eustis is another one to contact.