What I really want is to see available for sale is a 1gallon tank that can easily and quickly strap between tall style handlebars or to a rear rack.
Or a thin seat designed with a tank under it. Most bench seats have so much room under them.
Or an easy diy tube frame tank kit for frames that aren’t usually filled, no cap needed.....just vented up top so let’s say on a hobbit you could fill the main tank and the frame would fill and it output fuel thru the T fitting at the petcock. Of course you’d have to seal any bolt fittings into the frame. But having an extra 1/2 to 3/4 gallon without another tank on the bike would be pretty awesome