I have an ac110 (500) and a Remora skimmer. I to had the problem of where to put the skimmer. It would have been perfect on the side of the tank , like yours, but them my coralife light wouldnt fit as it runs the full length of the 10gal.
While starting this reply I thought I may have solved the issue of light interferance, moving the fixtures legs all the way over on one end and letting the other end of the fixture overhang the side of the tank. Thought it was a good idea but also did not work.
For now I have decided to run skimmerless, and I am selling the remora.
http://www.canreef.com/phpBB2/viewtopic.php?t=17728
(shameless plug)
As for your idea of hanging the skimmer off of the AC110, I would be a little nervous about that. First off, the AC110 (set up as a refugium) with live rock,sand and water weighs probably around 15lbs+ add on the weight of the skimmer full of water, and you know have alot of weight hanging off of the back of your tank. If the entire tank doesnt tip backward, then you run the risk of all that stuff putting pressure on that back glass pane. Which could cause it to crack or burst.
You would have to at least build a mini stand for both the skimmer and AC110. This however could be as simple as a few books or a couple chucks of 2x4 spruce.
Good luck.