I think this is my very first post (be gentle, eh?)
Don't tell anybody this but the Missus, (aka "thecuban") are seriously considering chucking everything we own into the front yard and taking off in a Class A. Thats besides the point, back on topic.
I'm involved in the Marine industry as a surveyor.
Every issue broucht up here is one that boaters have, and I must say, some are rather passionate about it.
Here are some ideas...
the + on first, - on last is a great idea.
Weak cells, one or more will drive you nuts and make your charge last a very short time, and shorten the rest of the banks life.
wander into your local tractor supply outlet & look for a group 30, or 31. They're real close to a group 27 size, and lend themselves quite nicely to the 12 volt needs of the sailors... those are some of the guys that wander offshore for a couple of weeks without the benefit of a genset. Or, if you've got the room, a couple of t-105 6 volt golfcart batteries work well too.
I'm not sure if this link will come thru, but, heres a shot