HGP3 had the same plan I came up with too. Mine is a little different. It incorporates the stock wiring with out cutting it and light on the K13S. (works on a S bike with a Yoshimura tidy tail bracket). I have about 30 of these for $22 each including postage. This is the last of a batch of 200 I made. Here is how to use this plate:
Remove your license plate. You will see three bolt heads that hold the plastic piece to be eliminated. Also you have to contort and get behind this mess and remove the two nuts (8mm) that hold the light. Save all the hardware to re-use. (caution, the studs in the light housing are just hot pressed into the plastic, the working torque on the nuts is light, maybe 2 lb./ft.)
The lamp in the light housing just wiggles out due to a snug rubber fit. Do this so you can reroute the wire. There are two alligator type clips that the lamp wire is tie wrapped to, depending on how you want to route your wire you may need to adjust these. They can be removed but watch not to damage the wire as they really bite the plastic. I suggest you cut the wire loose (tie wraps from clips) before you move the clip.
Bolt on the new adaptor plate when the old plastic stuff is off using the three original bolts. Mark the two angled pieces of plastic that stick down and take a hack saw blade and cut them off level to the ground. The plastic cuts easy you do not need the whole hack saw. Use some sand paper to smooth the edges. If done well and you want to go back to stock you will never notice these are gone.
Bolt on the lamp housing, (having figured out how you want to route your wire. I went on the outside to the left. A friend went under the plate adaptor on the left side.
Insert your lamp and you are looking oh so cool now.
Pm me if you want one. I mean, what can you buy for the bike for 22 bucks? Yes, that is a 250 lb. vise in the back ground. Holds front wheel carrier well for changing ball joints.
Mount Vernon, WA.
tire guy, I'll mount your tires.