I've never seen one on here, maybe try an atv forum site? Sounds cool though.
I would think an electric golf cart drive system in an atv would be too large and heavy. Not saying it couldn't be done, but probably more effort and money than it's worth. It would be an engineering marvel.
I do know there are electric motorcycles, maybe look at how those are done? See if you can source any of those parts?
Oh, and golf carts fit in the bed of trucks too....