I finally got to make a trip to a good hardware store!
I found a 3/4" conduit clamp bolts right up to the stem. I got some corner brackets and miscellaneous hardware to mount the headlamp. I looked at my motorcycle for inspiration, but found none there. The way it's mounted would only work if i had a triple, so scratch that. I guess i get the most inspiration by browsing through hardware stores, looking at things to see what i can work with.
Anyways, this is where i left off for the night. I'm not going to show pictures of my attempt at welding the clamp to the bracket. Let's just say that went poorly. No biggie, ill cut it off and get a new clamp. Maybe I'll just bolt them together instead of trying to weld thin steel. All I ever do in that stuff is blast holes