Gas Gauge/Sending Unit problem

Anyone have a cutaway of where the float is exactly at a full tank? It is submerged (cant go any higher) for the last 4 gallons? Seems a longer arm could really dial in the actual Ohms and then you could just get a blacked out meter movement and mark where a full tank is, and then every - gallon under that. These 4" arms are useless. Now a 12" arm like an old toilet float would give you less sweep but it would be more accurate as F would really be F and E could really be under 1 gallon.