James,
I'd debated between using the pole vs. plate SMV mount and talked myself into the pole ($1.00 more /w3tcompact/icons/smile.gif) thinking it would be more versstile, which it has. I figured I could cut it down if it bounced or vibrated too much. It moves a little for the length of the arm but my light is rubber and weighs very little. Also the SMV mount wedges in quite tight. I haven't found the light movement to be a problem. I have found the light to be very useful. I could see where a heavy metal light may bounce around more but you could shorten the pole.
Another (more costly method) is a company called RAM that makes mount for GPS, fish finders, etc. It uses a method of a ball and split socket that clamps on and off with an oversided tee nut. Something along that line attached to the ROPS would give you the same flexibility.
Others have tried magnetic mounts. If you have a pair of lights you could use the trailer stake pocket method to mount around the ROPS, one forward, one back. That is in the archives somewhere. Let me know if you want me to look it up.
The more ideas the better,
Michael