Steel Soldiers now has a few new forums, read more about it at: New Munitions Forums!
If you plan to run ALOT of 12v items or a single 12v item that has a large draw there are two safe ways to do it. You can either purchase a battery equalizer sized for your application that will discharge both batteries equally. Or install a separate 12v system compromised of a 12v alternator and 12 volt battery. Both have there pros and cons.
How hard is it to put heat in a A2/A3 that doesnt allready have it? How about a few cigerate plug ligther, huge roof mounted offroad lights, and a decent winch? Will the standard electrical system take it? Would the A2 or A3 be easier to do these things to?