Powder Coat Specification for Outdoor Aluminum

Any recommendations for a powder coat specification for aluminum that is to be exposed to both weather and sunlight? There seems to be about half a dozen types of powder and numerous ways of preparing the aluminum. Surfaces could be simply cleaned and deburred, they could be sandblasted or roughed up with a "time saver", or they could be iridited or have a powder primer applied. Again, numerous powder primers are offered.

A few of the powders stand out as bad for outdoor use (UV damage) but that still leaves many options.

Aluminum would be a mix of machined 6061T6 or cut and bent 5052H32.

This is a question related to commercial products but with potential world wide applications it is essentially a mil-spec temperature range without the need to actually do the mil testing. Water, humidity, blowing sand, salt fog, etc. are not formal requirements but we could at times install in demanding commercial environments with these issues.

I would appreciate any suggestions or stories from the past. Funny stories of failures are especially good.

Thanks,

Bruce