What years are you bikes? I have an 06 and hit the little flashy pump but didn't notice it for awhile then was paying attention and the final bar and pump were flashing. I didn't want to push the bike after having it for a week.
I've modified the fuel measurement system. I added a circuit board that measures the resistance of the sender and turns the appropriate bar(s) off as each full gallon is used. After the 5th gallon is used the bottom bar starts flashing to indicate "reserve". Since my tank holds a bit over 5.5 gallons, the "reserve" is about 1/2 gallon.