tunze make great skimmers, i like them as well, but it think the 9002 is too small for a 45g tank, and a 9005/9011 is too big to be asthetically pleasing in a in-tank configuration.
also, i would suggest one be aware that the tunze skimmers tend to over rated as far as tank size, IMO, and in most pro's opinions, so i suggest to use them on smaller tanks than what they are rated for.
if your worried about skimmer power/bacteria removal(which i wouldnt be), all you need is a skimmer that allows you to adjust the air and water seperately.
god knows there are enough bacteria products/methods to implement into your system, as well as nutrient additives, micro foods, copapods, etc...
use them if your that worried... or dump your skimmate back in your tank...lulz
so the skimmer to make everyone happy here is this:
CPR AeroForce 2 Dual Pump Recirculating Protein Skimmer
the pump that provides process water has an adjustment on it, and you can go buy a $3 1/8" gardena drip line/air valve at the hardware store.