New to Travel Trailers with a couple questions

6V batteries is old-school. You can get much better performance with less trouble, and less space, in new large-capacity (8D) AGM 12 volt batteries. Check out West Marine or your local RV center for more info. AGMs, unlike flooded golf-cart 6V batteries, do not need any maintenance and don't need venting, since they capture their off-gas and reabsorb it. Plus, they are more durable than flooded cells. YMMV