Externet wrote:

The tempting magnitude of lunatism could be an aircraft bolted onto a
registered catamaran (no mast); leaving room for an insurance inspector
to say "Nope. Cannot insure that thing" That could be a problem. No
intention to fly, just to go quite fast never taking off.

Let's be nice. I've been playing with just that idea. Sort of: a
flying boat without the wings.