Designing electronics and their enclosures for the outdoors
This isn't really a full answer but just to contribute.

Fiber Glass

I once spent a lot of time designing an enclosure that had to live outside in the full sun, near the beach so we had to deal with salt spray.  Oh and of course management wouldn't stand for any color changes in the plastics, and metal couldn't be formed to the pretty shape ID wanted...    

Most plastics either degraded in the sun or yellowed over time.   We had to pick white for the sun loading effect (shining sun down on the box heats it up etc).  In the end after working with our injection molding house and looking at tons of different plastics the only thing we found that met all our needs was fiberglass.   Something we hadn't even considered at the start.

Ants

Then as we started looking at what would happen if we needed a fan.  We started thinking about designing an air flow system that could still block water (although not salt fog)... Then someone pointed out that in the south there were problems with fire ants making their homes in electrical enclosures.  Here's a pic of some wiring damaged by fire ants:



Heat

In the end we were trying to work out a way with the injection molder to include a metal heat sink around which the case could be formed to get a tight seal.  Then some heat pipes from the main chips to the underside of the heat sink.  Not off the shelf but we were trying to do some crazy things at the time.  Never tested that to see how well it worked though.