A little background info first. The HMMWV is a 24v system and not a hybrid like ours, but some HMMWV versions had 200amp and 400amp dual 24v/12v alternators I found the reason behind this was to provide power to the transmission controller when the transmission became electronically controlled. The alternators on a HMMWV are located on the drivers side right where one of our alternators sit.
So my idea is this. Use the mounting hardware from the donor HMMWV (6.2 or 6.5) and install a dual voltage alternator. Some of the Deuce guys have done it and had to install a separate batter for 12v. Keep the 24v system the way it is, but switch all the 12v electronics over to the new third battery. This would clear up some room over on the passenger side of the engine for A/C, on board air compressor, turbo, or converting the alternator for welding just to name a few ideas.
I now open up the floor to critiques, comments, and general mayhem