to further realism and to account for aircraft that use more than 1 tank at a time please add a keyboard option to select more than 1 tank to drain from...
like on the p38 with its two engines each engine has its separate fuel supply and crossfeed to use the other engines fuel
could you figure out how to manually use 2 tanks at once since thats what the real thing did?
perhaps two fuel guages?
toggle fuel for right engine (all normal fuel options pluss option to use opposite engines fuel tanks to simulate crossfeed)