One thing that makes an incredible difference is to find a way to put some shade over the egg -- I made some supports from PVC pipe to make a ridgeline over my Scamp
and draped a tarp over that, staking out the corners, but it takes a while to set up. If there are trees, and the CG allows it, a rope strung between two and then a tarp over the rope (tie two diagonal corners of the tarp to the rope and stake out the other two corners. With the egg in shade and the vents and windows
open, it's surprisingly cool.
What's bad is when the egg is left locked up in direct sun during the day and becomes heat-soaked because it then takes a long time to cool off at night, even with a fantastical fan or the like.
See this new thread I just posted: