Back before there was integrated-circuit voltage-regulators the original and traditional way was to use a resistor. The most common was called Volt-A-Drop. Basically a wire wound resistor protected by a ceramic block. There were versions for a heater and separately a radio but each had an accessories terminal. They worked good enough but their wire wound resistors consume power and generate heat. You didn't want to use them long without running the engine. It would drain your battery. The fuel gauge and fuel level sensor do not consume as much power so yes you can use a single resistor. It is the most basic way to do the voltage drop but it is also the worst for voltage regulation.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
