baka, you can ride for a gallon's worth of miles until you need to refuel, it's not any different to having a reserve gas tap!
So what you're saying is that a 3.3 gal EFI tank with the fuel pump has 3.1 gal of usable capacity? I guess I've been close (too close if you ask me) at 2.8 gal on a fill up during a stretch on my last trip.
Sounds like you judged that very well! We each have to judge for ourselves just how far it is wise (safe?!) to ride after the light comes on, but there is still life in the bike for a good while, as you have confirmed.