Just A Car Guy: Iso Isetta beach car
This with a 5th-wheel hitch and a tent trailer done in nanoglass-coated basalt fabric. Rear entry door like an Airstream Basecamp.
Edit: the Isetta gets 78mpg already, and uses an altermotor starter/generator. One could swap out for a Buick Lacrosse water-cooled 20hp altermotor and add a small battery pack to make it a tow rig.
Leather helmet and goggles.