inverters and air conditioners
An inverter large enough to run an air conditioner would probably suck your batteries flat before the cabin got comfortable! The power just isn''t there unless you have a genset of some kind.
Can''t recall the dimensions of a 105 battery. Are they the same size as a golf cart battery? If so, Blue Sea Systems(they have a web page) offers battery boxes for two 6 volt golf cart batteries. As I recall they run abound 80 bucks each.