I don't have a Sharknose, but on my '11 Street Glide, when I added a King Tour Pak, I fitted HogTunes speaker pods on the Tour Pak and added the wiring for the rear speakers myself. I even sourced hollow bolts for one of the mounting points, and ran the speaker wire into the Tour Pak and behind the lining (so it wasn't exposed). I too ran an amp and simply bypassed all the factory speaker wiring (and overcoming the lack of rear channel wiring) by running my own outputs off the amp. That made my application simpler, and since I ran speaker wires in the wire trough with a quick disconnect setup, I could remove the whole TP in about 3 minutes. You may also need grilles for the speakers: I used the Harley CVO style grilles on my pods since the Pioneer "grille" didn't really cover the speaker well.
If you're running the HK head unit, I BELIEVE you may still need to have the "Fader" function enabled by the dealer so you can have that function; that way you can balance your soundstage a bit better on the deck (and not by playing with gains on the amp- which is not a dynamic means of changing the output).
You can still get the Hogtunes pods, or E-Glide Goodies sells pods as well. Note that I did have to take a razor-knife to the Hogtunes pods and cut out a bit of the opening to fit 6.5" speakers (Pioneer TS-D1605R).
My Post Count prevents me from linking to sources for the pods, but the HT pods are on Amazon, and E-Glide Goodies has their own site.