[ Closed ] running the gameboy DMG on li-po batteries

i want to make my gameboy run on li-po batteries instead of aa ones.
now i could either wire up two 3.7v batteries to get 7.4v, or use a step up regulator on one battery to go up to 5v.
the question is, which would be more feasible?
im guessing its better to use the step up regulator, since you can use twice as many batteries for the gameboy then.
im talking about the DMG.