re: "don't get a marine/starting battery for house use. get a deep cycle type, no CCA on it."
all batteries have a CCA, it's just not listed if the marketing for the battery doesn't think it necessary. You can easily measure it if you want and it might be a good thing to know if you run an inverter in your RV and like to use a microwave to heat up a cup of coffee or something.
Also. if you can find an objective definition for 'deep cycle battery' that is backed up by a pertinent and useful empirical measure, please let me know. I've been looking for years and so far come up empty.
Do get a battery from a retailer who sells a lot to folks who use them like you do and will stand behind what he sells. Then go by specifications, warranty, and price.
I would add since RVers are somewhat mobile, to also worry about where you can get replacement under warranty. that is what is great about buying from WalMart. almost as common as a $9.00 a cup coffee place.