Most Important - Keep the moisture off the boat and out of the bilges and airflow. The more airflow the better. If you have day and night vents on the boat now, are they less than 5 years old? If older, buy brand new ones, if less, buy new batteries and make sure the solar
is clear. Don't count on power from the yard - invariably, it will be unplugged by someone or go out for whatever reason, so you want the boat and any systems to be autonomous and in your control.
Whatever you can do to provide good airflow through the boat while keeping it sealed up to the elements, the happier you will be when you return.
You should have no problem finding someone to pay to watch the boat and keep it cleaned up and ready for what happens next. Many times, folks find they are not getting back and not in a place that makes sense to truck the boat to, so end up on the market. Spending a few bucks a month for a licensed and bonded company to keep it clean and aired out is a good investment.