Which Morningstar MPPT
controler is it?
A lot of controllers will enter an automatic timed absorption phase every 24hours.
If the batteries are fully charged 2 hours on the absorption voltage is not good for the batteries especially at high temperatures.
The ideal is to adjust the controller so the charging
algorithm is suitable for a fully charged battery
Reducing the absorption voltage, absorption time and float voltage are ways of doing this.
For example absorption voltage 14.1v for 2 mins float 13.4v. These sort of settings will keep the battery
in the best condition.
Unfortunately many controllers are not adjustable like this. Sometimes a suitable compromise can be achieved by selecting the gel battery option (when your batteries are really flooded batteries). Typically the voltages on the gel setting might be 14.2v for 2 hours and then 13.6v still a bit high for long term storage
but much better than the "correct" flooded battery voltages.
Connecting only one panel can work if you have a very small panel but generally the smallest panel is enough to push the batteries up to absorption voltage, so this does not help.
Leaving the batteries disconnected the SOC of charge can become too low due to self discharge. Self discharge is greater at higher temperatures.
If you can list the model of your controller (also have you got temp compensation installed) I will see if it has any suitable options for long term storage
It would help to know the typical temperatures you would expect while away.