In order to buff the clamp collars I use a buffing wheel and some Tripoli or stainless specific compound. These wheels and compounds are available at Home Depot and will fit most bench grinders. IMHO every boat owner could benefit from a buffing wheel. I use mine all the time.
I get my wheels from Grizzly and some of my compounds too.
Grizzly Buffing Wheels (LINK)
Grizzly Buffing Compounds (LINK)
Home Depot / Ryobi may be easier but the quality of the wheels from Grizzly is much better.