Keep in mind if you plan on towing your trailer over PUBLIC ROADS you are required by DOT to have a working battery for the ENERGENCY BREAKAWAY SWITCH setup that will stop your runaway trailer in the event of becoming disconnected while enroute.
I doubt if the dealship will replace any batteries under warrenty. This is more or less your responsibility to keep the batteries operational.
We all have to learn how all of this works and not get into those circumstances. My batteries were installed in 2008 and still are performing well...
Roy Ken