I hear you, but it's a stretch; drunken or negligent motor boater rams you. Some months after the fact the other guy's insurance company claims your anchor light wasn't on or was non-compliant? Really? Based on what?
This happened to me a few years ago. I was anchored and an idiot in a 32 foot sailboat rammed right into my starboard beam right amidship. He'd just left a yacht club - draw your own conclusions about his condition. He was, however, quite contrite and his insurance company paid. I had our backstay anchor light up, in a small anchorage right outside a marina/yacht club. This was a very, very low traffic area and an anchorage I'd been visiting regularly for many, many years, well lit by the marina, the Golden Gate Bridge lights, a Coast Gard station and my "down low" so it could be seen anchor light. It evidently wasn't. BUT: he wouldn't have seen one up high either!!!
This "is it legal?" argument has be "raging" across the internet for decades. It's beginning to get tiresome. Why? Because NO ONE has ever been able to come up with an example of anyone being denied compensation because of the lamp being used in any anchor light. And this is internet boating forum-wide; I read lots of boating forums. NONE.
This has been debated on CF in great detail. The conclusions I've drawn are quite simple: You're much better off being seen; if you have any doubts, then simply run BOTH the one at the mast head AND one further down.
What's so hard? It doesn't have to be either or, does it?
Davis Mega-light? You'd need a 12V socket.
I just hard wired mine in. You can do that, ya know.