I put an UltraGauge in my Axis and told it I have a 50-gallon tank. I fill up when it says I have 50 miles to empty knowing I have an additional 5 gallons/50-ish miles in the tank if I need them.
I've only let the idiot light come on once when I was pushing hard for home. Put 53.5 in that tank that time. Way too close to empty.
Regards,
Randy