After few hrs now, temp is 33/34 C . While this is very good, it is interesting how having the side panel fully removed makes 3/4 C degrees difference.

Also, weather is improving and I wonder how things will be as it gets warmer.

I am considering making a second similar hole (with a net or dust filter of some sort, this time) not far from this one. Not sure it would pay off, but it is actually a fairly easy thing to do and now I have all I need. Mmmh...