Well I am pulling on advice from my father and mother who have been in some kind of an rv for more than 80 years total time...lol...they are old but still kicking!!
My father has pulled his batteries out the boat and 5th, charged them up and then placed them on a block of wood and in the corner of the shop. The wood helps the battery from discharging, this is a source of debate but I am here to tell you it works.
In the spring he tops them up for a charge and back in the unit they go. Sounds like a lot of work and yes it can be difficult to remove and muscle into your house but well worth it and cheaper than spending 100.00 on a new battery every spring cause it died through the winter. Mike is also right that if it breaks open from freezing you will have an acid mess to clean as well.
Using this method my father has made batteries last for more than 10 years and they are just fine to use still lots of power. Personally i used a trickle charger on 3 batteries this last winter and 2 out of the 3 died. No power failures or anything else to kill the charges or make them do funny things and they were hooked up properly ( I pull wrenches and drive truck ). Will I use a trickle charger again....no...will I pull my batteries....yes.
Hope all the info helps.
Glen & Robyn (A.K.A. Puff & Crickit) Full Timers..
2006 F350 6.0 with 3.73 gears, 4X4, Extra-Cab Long Box, Oil/Tranny/P.S. Coolers. Coolant filter. SCT Livewire.
2011 Cedar Creek 36RE, Auto levelers + too much to list..!