I think the newer cars with the factory radio might have some issues with losing battery power. It is an anti-theft measure that requires you to enter a security code upon hooking up the battery again. You might want to check on this and make sure you have the security code first.
It may turn out that for a short trip of a month or two you'd be better off leaving the battery connected.
Some of the devices G-Benz mentioned have a small fused lead that keeps power going from the battery to the radio. That's meant to be a security device when you remove the knob - you can't start the car. Of course you can take the fuse out too and prevent battery drainage.
Have a nice trip. Someone with a newer car than mine may have more tips for you regarding the radio security code. My cars are all too old and have aftermarket radios anyway.