I think this has been done. If they fit, you will not be able to charge the batteries in the light, using charging cradle, due to Streamlights prorpritary battery design. See top of Stinger battery pack. Also, you will need to add nipple to batteries for positive contact, and overall length may be a issue. Some flat top batteries (Aero) come with a raised contact area on positive end that will serve as a nipple. Runtime will be reduced, compared to UltraStinger, as most 1/2 sub C's barely make 1000mAh. Would be a bright sucker, though.
Bill