Well, I still go back to your ORIGINAL idea...the FLashpoint 320 MP lights have a VERY affordable, roughly 15 ounce battery, dedicated to their system. The 320's are convection-cooled, so there will be no issue with a cooling fan sucking all your battery juice on-location. At the price of the Flashpoints, you can afford to buy one or two as spares....I mean, good gosh, they are LOW-priced monolights, but with user-changeable flashtubes and user-changeable modeling lights. These things have been made for almost 20 years now...there simply is no better value in an AC/DC monolight with a small and AFFORDABLE battery pack designed expressly FOR the MP-series Flashpoint monolights. These things cost less than 1/3 of what a Canon 580 EX-II or Nikon SB-900 speedlight costs...and if you go with "other" monolights, then you will be committed to buying a sine wave type battery/inverter ($200 to $450), or an expensive Quantum Turbo battery. If you want a light, umbrella, stand, and a location battery, there is NO OTHER system as affordable as the Flashpoint monolights.
The Calumets and the Elinchrom and Alien Bees will cost hundreds and hundreds of dollars more, for about the same flash power.
Adorama is probably the second-largest photo gear retailer in the USA. They have been importing and selling the Flashpoint monolights since the early 1990's, to my recollection. 160 watt-seconds of juice discharged through even a middling efficiency flashtube and with a decent reflector is going to put out PLENTY of light for many,many situations. Keep in mind, many speedlight flash unit makers describe the power of their units with the flash head zoomed toward the telephoto end, as a way to artificially inflate the power...while MOST monolights will have their power in Guide Number with a "standard" reflector which might very well cover 110 degrees. In other words, with the right reflector, a 25 watt-second Speedotron flash head's pop! will light half of a room, while a full-power flash from a $400 speedlight will just light the center of the kitchen table...