I always think of doing wacky things like this. I usually get to the testing stage when I realize that any gain in efficiency is going to be lost in doing the custom work, not to mention that when the modified/specialized thing I've tinkered together dies, it's replacement will need to be modified too.
So, sure, you CAN take the DC from the generator and use it to charge batteries. But wouldn't it be better to just take the hit in efficiency in order to gain drop-in serviceability? If you use a generator to power a charger, then if any component takes a dump, all you have to do is throw it in the ocean and plug another one in. But if your system relies on custom components, you are stuck until you can rig a new thingamajig.