you need to have some way of knowing you have your brake lights switched on or off or you are going to get into trouble with the old bill, or someone ram you from behind, both im sure you could do without.
i dont realy see how brake lights are a problem whilst lamping, they have never bothered me, but, if you want them blanked, would it not be beter to devise some sort of shield over the lamp or just gaffer tape them over so you have to pull it of when youve finished.