I'm not buying a new fork, just looking to use what I've got.

Turns out that the stem I'm looking for really doesn't exist or is really hard to find, so I'm going to leave that idea alone for now. The HED unit looks interesting, but I'd have to order it online (the local shops don't carry it) and I'm not sure it's quite what I want either. (I'd like to hold it in my hands before I buy it.)

I went ahead and reconfigured my Bar-Xtender, and I think this works better than what I had before. Rather than hang it off the stem downwards, I'm doing it off the middle of the bar through the hole in the face of the stem. This gets the lights mostly out of the way of the cables and improves on that aspect of things.

It's not quite what I was after, but it's pretty good.