I didn't dig in to the whole thread , only the first few and last few pages- but take a serious look at russell brown's of pt watercraft (wa usa) highly developed solution to this exact question. tornado (beach catamaran type) hulls with 20hp efi outboard, and lightweight pod.
https://www.offcenterharbor.com/vide...t-motor-boats/
those interested could find more info via a dedicated google search.
The propulsion (outboard motor) could still be optimized, electric? propane? (perhaps), diesel ? at least diesel ..ought to do better efficiency than a gas burner.
The takeaway; long waterline (hull length to beam/width ratio) , multihull, extreme low weight