The ones I flew had a boat rego on the floats and I had to have a boat license. Don’t know what the rules are now but I don’t see boat regos on them anymore.
Never flown one with boat rego, never been asked for a boat licence. I did however see the "authorities" being told to "piss off; ya got no authority, on the water it's a registered power boat, in the sky it's controlled by the Commonwealth" by a private float operator. He had landed where "they" reckoned he shouldn't. "They" backed down.
I think old mate had a great idea, I am just not that into his testing location. Hope he "flies" it again. Ironically, the Caspian Sea monster featured on "Abandoned Engineering" just last night.
Eff off I say to the idiot agency.
Amen to that aroa, wish more would join us :-)