Make the TrackIt app in the truck reference the current weather forecast for temperature to look for temps below freezing. If temps are going to be in a freezing level over the next "X" hours/days (configurable time frame) that the truck is/may be parked that an alert/reminder displays at logout instructing them to drain the water lines (Customizable message).
I understand the ability to configure this type of status reminder/question already exists, however, adding in the temperature reference would be helpful in spring, fall and winter as it would eliminate having to enable and disable it during certain seasons.
The ability to "schedule" timeframes for certain status questions/reminders would be helpful as well. Schedule when it would be enabled vs disabled based on calendar dates.