Can't help with specific models, but a comment regarding batteries. With the availability of batteries like the "Concorde Lifeline AGM" and similar products, you can put an extra battery anywhere there is physical space - no need to worry about ventilation. Most campers have a place (under the bathroom sink, in the generator compartment if you don't have a generator, bottom of a closet, etc.) where you can stow an extra sealed battery which can be wired into your electrical system. So I would not let battery compartment size totally determine your choice. Also, make sure you add at least 1 large solar panel to the roof to maximize boon-docking flexibility.
Happy Camping!
