I went with option #2, the 2nd fan is attached right to the chimney stack and it's blowing all the air out now, no back pressure falling back down. I can go outside and in the dead of the night if I listen, I can hear the air escaping the top of the chimney now, so I think I'm good. Temps are ROCK solid now.
As for the portable AC, I did do an "elephant" mod to it. I used a 8-6" reducer that fit perfect over the front, then I run a insulated duct to the tent. Not a drop of cold escapes, it all goes to the tent. I also took apart the AC and extended the thermostat so it reads the temp inside the tent, so when I set the portable AC outside of the tent to 75, it controls the temps based on the air at the top of the inside of the tent.
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Since I'm in a basement, yes I could have cooled the room the tent is in, but it's not insulated and I figured 90% of that cold air would have been lost through the ceiling, etc and not in to the tent, thus forcing me to run it 10x longer.
Thanks for all the input though, it's running nicely now