[EricH]

Someone asked Q&A, and the response was: "Rule <R58> requires that the Robot Signal Light must be visible when standing three feet in front of the ROBOT when it is in the STARTING CONFIGURATION. There is no specific rule regarding the visibility of the Robot Signal Light when the ROBOT is in a PLAYING CONFIGURATION. However, it is strongly recommended that the Robot Signal Light be mounted in a location that is easily visible at all times. The light is used for diagnostic purposes by field personnel. It is to your advantage to make sure they are always able to see the light, to assist in identifying and correcting any problems that may occur during a match."

As for mounting the cRIO, how you do it is up to you. Use caution, though--it just might have to last you for several years!