I scored a white tarp today thats very thick and durable. My plan is to cut it to a size that will allow me to run it 6" up the wall on all 4 sides. So basically 1 foot longer and 1 foot wider than the box.
I monitored the temp today and the highest it got was 82 degrees. The outside temp was 80 degrees at that point, during the hottest part of the day. We're not going to be seeing too many more 80+ days this year, so Im not going to be installing any fancy air conditioning setup... yet. This crawlspace is attached to a room with a powerful exhaust fan (my smoking room) that vents directly out the roof, nowhere near my neighbors windows. My plan is to run a 5" box fan and dryer hose. I will suck the air out of the chamber and vent it directly into the path of the big roof fan. Also might put another 5" fan just sitting inside the box to circulate air.