My fan runs alot. Even at 15 degrees below freezing the fan will continue to run for several minutes even after I stop the engine. Even, or oddly enough, especially after high speed runs when you would think there would be lots of airflow. The temp light never comes on though. I wouldn't worry unless you don't hear the fan running. A manual fan switch is a great mod to not only run the fan whenever you want but also to check that it works before and during a ride.
Adding a temp gauge still sounds like a great idea.
Adding a temp gauge still sounds like a great idea.