I've enjoyed looking through what I've seen so far in this thread.
It's great to see someone truly enjoying not only the grow but the setup too, It's also nice when a grower puts a lot of time and effort into their product.
I especially like the three pc fans that will blow air up through your plants, clearly someone knows about convection.
Just a quick question though...Have you considered using the out take fan on it's own (seeing as it could completely control the temps of your chamber) and having a separate fan/ducting for the cool tube as they are originally intended?
In theory you could even use a small bathroom extractor fan for the cool tube. (although this is not ideal it'd do the trick)
Apart from
that, Happy growing!