Taz wrote on 12/31/69 at 16:00:04:Maybe one built into the gas cap would work for you if you can find one that fits.
Lambrettas from the 1950s (2stroke scooters from Italy) had a fuel cap with a built-in fuel gauge, it was very basic yet very dependable; little more that a very long fuel cap with an integral float that would push a needle. The nice thing was you could see at a glance how much fuel you had
; the bad thing was it never had the locking cap option, and with the first fuel crisis of 1972 punks would syphon all your gas at night.
AND... it was fitted under the seat ???
Anyway, I'm sure that somebody will think up the modern equivalent to the Lambretta's system
Maurizio