@ Navy Dude - If I get to do it all over again.  I wouldn't bother with a small shed.  I would build a large structure where I don't need GFI.  GFI is simply not good with PDUs as the more devices you have connected, the more likely 1 device will have issue causing everything to trip.  The constant breaker tripping even during drought weeks tells me it's not humidity.  I've replaced breakers, and the issue is very random and it can happen at night or day time.  This can occur on any of my 4 GFI 30AMP breakers.  This is getting annoying and costly.  Going non GFI 120V is not an option for me as that would consume double the amperage and going non GFI for 240V would be asking for trouble and potential death.  It's not worth the risk.  Cooling wise it's working well but the best you can get with air cooling is same as ambient.   If the outside ambient is 105-110F, I would recommend  turning off for the peak hours where it reaches those temp.  You would lose only a few hours of revenue but will avoid costly damages.  The rest of the non peak hot hrs should always be well below 100F making it safer to run.