Do Not Do That.

Use a random orbital sander with 60/80 grit pads. J.

Agree with John. I think your asking for unnecessary problems with the router. an orbital sander works fine.

Then again, if your looking for an excuse for new tool: think about a fein multimaster. you will still have to hit it with a sander though

Thanks for the responses guys. I do have access to a multimaster tool - so I'll give that a whirl. You both said NOT to use a router, but neither said what problems could arise. Just curious - can you share?
I'm not trying to get out of sanding......I will be sanding the entire deck. The reason I want to triim first is that I'm working with 1x6, so the plugs stand much higher than with 5/4.
I guess I'll try the multimaster, and also try just sanding only and see which works better.
Kim

The router would work but it would be painstakingly slow and even with the steadiest of hands, a little too much of a hit to the plug will send it into the universe. You would have to shave a miniscule amount making many passes on just one plug. Not worth the effort or frustration if you happen to slip too deep into it. Kinda like those volcano hikers who get as close to the edge as as they can to get a kick while it's boiling beneath them!