First questions are whether you have ever seen the optional red over
green lights used?

Not ever -- that I recognized. I'd be confused if I saw it, and I try to
keep up on these things.

Jeff,
You might be confused at first, but at least it would get your
attention. You might not remember from your reading of the regs what
the lights meant, but you would know that it was something different.
And my bet would be that you would stay clear of it until you figured
out what the vessel was.

In my opinion, a saiboat under power is a powerboat and should be so
marked.
No question about it. But, by the same token, a sailboat under sails
alone is not a powerboat and it is actually illegal to use the
powerboat lights when under sails alone. If I were to be under sails
and use the powerboat lights and then had trouble maneuvering, I could
be held liable.

The steaming light up the mast is pretty distinctive and usual, so other
boats can tell you're slow.

Maybe on a lake where most of the powerboats just use an all-round
white light rather than separate masthead and stern lights. But along
the coast where there are larger powerboats, it is normal to see the
masthead/stern lights combination. So, seeing a steaming light up
high could just mean a large powerboat that could be very fast.

Being able to determine the boat's heading by the lights is VERY useful,
too. Red over Green wouldn't afford that visual clue.

I must not have been clear in my earlier post. The red over green
goes at the peak of the mast and is in addition to the red and green
sidelights (or combination light at the bow). You would get the
heading information from the lower lights and the type of vessel from
the upper lights.

Lee Huddleston
s/v Truelove