Lets not over think this folks. Does everyone remember KISS, KEEP IT SIMPLE STUPID!
These lights are all approved.
http://m.tmart.com/5-LED-F105-Safety...d_p124042.html
http://www.ebay.com/itm/1-5-Red-Mini...3D350630312603
http://www.amazon.com/Brightest-Rech...ike+tail+light
Here are the official Rain Light guidelines:
Light assembly must be securely mounted to the rear most point of the machines tail.
Light must be mounted and functional when machine is presented for technical inspection.
Light may be removed during dry conditions.
No OEM taillight assemblies.
Light may be self powered (internal battery) or connected the machines battery (must have an on/off switch if wired direct to the machine)
Light must illuminate solid red in color when powered on.
Light may not function as a brake light.