A longer arm wouldn't help. Its the ram ball sits down below the top of the resevor and its to tight to get the Ram arm attached to the ball next to the resevor. If there is a small extension made that raises the mirror post up, then I can attach the ram ball to it and it will work fine.

 

Check on a site that sells RAM, take a look for the replacement for the MC mounting clamp, that should work for you. Like this:
RAM Motorcycle Brake/Clutch Reservoir Base with 1" Ball