First, lets start with what didn't work... Rear speaker harness p/n AO45180123 from Cycle Giant.com Wingstuff $29.99
Arrived today and was not a fit for our bikes. Rather than return and wait, I dissected the plug for the spade ends and wire, then used that to plug individually into the bike harness.
I made the bracket out of 1/4 in steel and painted them Matt Black. They are pretty sturdy.

Now what worked...These little Pyle PLMCS36 are just the look I was after. The are not amplified and they will not overpower the front set. My goal was to just add a little something for my passenger to make up for the sound I may have been blocking from the front.

The fader is functional although I didn't see a balance control on the radio. I'll look closer tomorrow. I also hope to ride tomorrow to test these speakers but as I said they are more for my passenger.

If I raise the backrest by using a good size aluminum spacer, I could see bolting on larger speakers as part of the backrest extension.

I could see a total upgrade but I hate to use the saddlebags for that (amp and or speakers).
I don't want a rolling Boom Box.

20130518_192356.jpgF6Bspreakers rearview.jpgSpeakers from the front.jpg

I'll update after I use them a bit, but I like the way they look.