I find it interesting that no one mentions fact that there is debate about curing tempretures involved in powder coating causing aluminum alloys to become weaker leading to possible failure.
I'd make darn sure you know tempretures and curing time your powder coater uses. Some use temps as high as 400 degrees which is getting close to temps where metal structure can be changed.
Here is some discussion on topic
http://www.eng-tips.com/viewthread.cfm?qid=151053