Probably no one is reading this by now. In any case here is another thread on powder coating of aluminum: http://www.finishing.com/322/04.shtml
Again, here is the start of the thread: We do lots of aluminum work around salt water. Everything we do gets sandblasted and powdercoated. We now are seeing corrosion forming under the powdercoat , blistering , and peeling .
We do use stainless steel hardware (screws , etc.)and we know that this is a bad mix but the only alternative is steel hardware which rust almost overnight.The blisters are not just around the screw areas though, it is all over.
Again, sounds a lot like the problem that I and others are observing with the akas.
That thread you posted was more of a question Keith and the answer below is:
Your problem is definitely pretreatment, at least the bubbling and lack of adhesion. Aluminum must be chemically treated prior to powder coating to get any kind of outdoor performance at all. Look to a good chemical company to provide you with a fluoride bearing treatment and a reactive non-chrome final rinse. Then get clean rinse water and you're all set. If you don't have all the equipment for that consider jobbing the powder coating out to someone who does. It'll be cheaper in the long run.
If the surface is prepared correctly powder-coating is very effective and very cost effective...Pirate