No not at all. Disconnect the (black) Negative cable first.
You can then remove the automotive battery and store it inside. Give it a nice charge and then it should be good for the period of storage. I would also store the battery on a piece of plywood or rubber mat so the case doesn't come in contact with the ground.
I don't think that I would keep it on a continuous (trickle) charge unless it were connected to the chassis circuitry.
Reconnecting, positive first then negative.
I'm sure that you will get a lot of replies from the other members as well regarding long term battery storage..