[IMPOSSIBLE] Remap 0 EV

[psmith]

I have a 6D and a 60D, both of which i find underexpose (Subjective i realize) between 1/3 and 2/3 of a stop. I generally just add that amount of EV to compensate under normal circumstances in AV or TV modes. The problem i have is under changing lighting conditions using Manual with Auto Iso. The pictures always come out underexposed and i don't want to switch back to manual iso selection. Remapping what the camera sees as a proper exposure would solve that. Is that possible?