Hey There,
I had an AP12 myself. I dont' think there are any quality protein skimmers you can get with the hood on. I know most nano skimmers do a pretty crappy job of getting gunk out. I wouldn't waste my money on them.
With a tank that small, some good LR will provide plenty of filtration. replace the stock pump with something like a MJ1200 for better flow. Maybe take out the bioballs and ceramics and add some LR rubble. Just make sure to do your water changes like normal and you should be good to go.
Good luck and let me know how everything works out!
-Raz