It's true a dual 6V battery setup will hold more capacity, but taking good care of a single 12 is fine IMO.
Mine's detachable/removable, with a tender on the front, so I can keep it warm and topped off in the garage rather than freezing and self-discharging in the trailer when i'm not using it.
I can go through the day running the furnace and a light or two off a fully-charged battery, which is nice if I take the pup along. Can keep him warm and comfy in the trailer while we're out sledding and not have to deal with the generator.
Spewer of the poignant non sequitur