You can increase the idle timeout for admins to a max of 8 hours.
To minimize the risk of someone accessing the firewall during this long period, you could create a new admin ' monitor' (or such), uncheck all menu items he' s allowed to use and change the remaining to read-only. If you disallow all menus, the SYSTEM menu with the dashboard remains.
You can even put the traffic monitor (or multiple instances for several interfaces) on a customized dashboard.
"Kernel panic: Aiee, killing interrupt handler!"