Quote Originally Posted by m00dawg View Post
It gets hot enough where I live where I would definitely need air conditioning which seems to be the biggest complication I'm running into, since I'll need an AC unit itself, probable radiant barriers and perhaps even insulation.
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Thoughts, concerns?
It it were me I'd be looking at a ductless mini-split system for HVAC.

As to ventilation fans, always remember that fans like to pull, and they hate to push. Said another way, trying to blow air through a duct can be like trying to push a rope. Because air is compressible. Far better (or at least more efficient) to locate the fan itself on the outside wall of the structure and on the other end of the duct that runs to the light-tight louvers over the sink.

And you really should insulate the structure at least to your local building code requirements. Go higher if you can.