Removal of batteries during cold weather storage

I have a new Big Country with two 6v batteries. They were fully charged when the unit went into storage about a month ago. It will be in storage for another 5 months or so before we use it. We are in a cold climate area with temeratures well below the freezing mark for long periods and there will be several very cold periods of -20 to -30 and possibly colder. I used to leave my batteries in our RV's when it was parked near the house and I could plug it in a few times over the winter, however we have moved and don't have room now to park it in the yard. Any advice is appreciated.

Remove the batteries to a nice warm place and keep them charged. They will last much longer. I'll leave the discussion of charging method to others.

To add to what branson4020 recommended, purchase a "battery Tender" which is set-up for dual 6 volt batteries, hook it up to both of them and don't look back until your ready to reinstall them in your RV...

I really don't know if what I do with my batteries is best, but it's the way I've always done it, and it has always worked out. I live in a cold weather area so I remove the battery from my 3400RL as well as the battery in my mower. I put them in the garage (not on the cement floor) and put the charger on them about every month or so. I do know that if a battery is allowed to completely discharge, there's a chance it could freeze and crack if the temp dips below zero. JMHO

I have always left my batteries in the coach all winter with temperatures below zero at times. They are too heavy to drag around. I never had a problem. Be sure to disconnect the batteries from ALL loads either by removing a terminal connection or by a battery disconnect switch. In recent years I have used a roof-mounted solar cell to keep the charge at 100%

I remove the battery and keep it on a wooden shelf in the basement with this charger hooked to it - http://www.harborfreight.com/automatic-battery-float-charger-42292.html - all of our RV batteries have lasted 4-6 years.