This has been done, but that never should stop you if you want to do it.
The "it'll use batteries" part is the MAIN "freakin ridiculous" part of the plan. If you're going to do this, figure out what size power adapter you require and hack one of those. Constantly putting batteries back in that thing will wear QUICKLY on you.
Other than that, I'm wondering why you just don't build a bartop MAME machine - you'll end up with more games, and probably get more use out of it.