Relying on the disconnect switch to fully disconnect the batteries is generally inadvisable as often there are at least a couple little loads that are not disconnected, such as the radio memory circuit or the CO or LP detector. Even a tiny load over the course of months adds up to a good bit of charge usage.
If the prevailing temperatures at the storage area will be below freezing, charging fully and disconnecting is fine. If the temperatures indoors are somewhat warmer on average, or there's concern about theft, it would probably be wiser to pull them and store them elsewhere where you can at least periodically give them a bit of a charge. (I'm assuming there's no power available at the storage place; if so, the best answer should be pretty obvious.)