Just like Texas Sam said, if you store on wood or plastic you will be fine.
DO NOT store it on cement. It will drain faster.
Typically any battery will lose about 1% of it's capacity a month.
If you have it stored and disconnected for a long period of time such as 3 - 6 months, it would be a good idea to "Top it Off" or charge it the day before you reinstall it in the Trailer.
HAPPY CAMPING!! :D
Daryl and Sandy
2013 Eagle 314BDS
2014 Ford F150 Platinum, 4 x 4 Crew Cab with Ecoboost