not wanting to seem like a smart arse but just read EESDL's post as well and boost pump failure in a L/R is not as clear cut as you state.
you would need a dual boost pump failure to lose all capability to transfer fuel, and dont forget that if you have much less than 280-300lbs on board then you have used all of the usuable fuel in the forward tanks anyway so a dual failure at that stage is of no real problem (notwithstanding sucking air etc.)