Read what charger does as wording is often misrepresented.
Trickle chargers are design to keep the battery topped off overnight. They have low amp, but high voltage and left for long time will boil your battery dry.
I have been using
THOSE HF maintainers since when they sold for 4 bucks, what makes about 25 years.

But everything in this life is subject to failure, so having maintainer on, you should check it once a month.
For 3-6 month dry storage I found disconnecting battery clamp the easiest and really foolproof way to go.