If it's a flooded cell battery and it's fully charged when put in storage, there is no reason to trickle charge it. It will hole most of it's charge over the winter. I do that all the time with my farm tractors. I leave the start batteries in them but break the negative side with a knife switch. They start fine in the spring and it gets cold here.
What people don't realize is it's HOT weather that destroys a battery, not cold weather but the reason batteries fail in cold weather is because the battery was already compromised that summer but when it's cold, it takes appreciably more cold cranking amps to turn the engine and the compromised battery cannot supply them.
2015 Backpack SS1500
1997 Ford 7.3 OBS 4x4 CC LB