I think that the ambient temps are very important to keep in the low 80's. If you look at the temps in Ghana, it is always very warm to hot and so I beleive that the air temps are always quite warm. I would be concerned with ambients under 77F.

As for finding shade, yes, and yet the ground also stays warm from the constant warm temps and sunshine.

I keep my ambient temps up using radiant heat panels since where I live is cold and my house is kept chilly. I have not had a snake become ill with an RI (knock wood!) and I believe it is due to my temps beings kept within proper ranges (82 cool side and 93 warm side) and my ambient temps kept at 82F.

So, in essence, I disagree with the statement that a basking spot of 90F is "regurgitate widespread misinformation".

Just my thoughts....