Educated opinions gladly accepted on this one, and thanks up front!

My '09 came with the Ultra style rear fender lamp and top-mount tag light. I swapped it out for the under-mount tag set-up that comes on a standard Road King and the Electra Glide Standard. This one has that LED tag light. The plug that powers that tag light goes into the socket where my fender lamp plugs in. And, the electrical backing plates are the same, so there is no extra socket. The FHLX merely uses light from the clear area below the lenses they use. I mention that because I compared different bikes hoping there was a different style back late available.
So here's the deal, I have the run/brake/turn signal conversion on the bike and it's fine. However, since I needed that socket to power the tag LED, I simply left the rear fender light unplugged because I wanted to eventually buy the kit from Harley that turns that rear fender lamp into an additional brake light, similar to the effect that's been available for the Street Glide. So now I have that item and I got to thinking, even though I can properly splice a wire where needed, how can I splice it so that the fender lamp works as a brake light like it's supposed to and not have the tag light vary its light intensity. Not so much how, but where am I to splice in so I get appropriate function.
I want to think this one through because I just ordered a brake light kit for the TourPak luggage rack I'll be using and since I'll be making it a detachable unit, I want to wire it up correctly. I can do it OE style with Deutsch connectors and whatnot for disconnecting the TourPak, I just want to do it cleanly without having to re-do it later due poor planning.

Thanks in advance for any assistance.

 

I'd like to see some pics of your tag relocated.I'm at work now ,but I'll have a look in my service manual when I get home tonight and see if I can tell you which wire to connect your tag light to.I'm doing the same mod to mine when I get her out of storage.
Dan