Ok. I spent the last half hour rigging up a battery holder / connector / switch combo. For now I just hard wired the halogen into the battery pack since I didn't have the male connector for the system available and had limited patience for how much fussing around I was willing to do for a proof-of-concept test.
I've just plugged it in, and on fully charged batteries this thing is very bright. Now to sit and wait to see how long it will stay that way.