All three of my LF cameras have folding hoods. They are really nice for (A) a quick overview of the composition and (B) coarse focus. They are useless for critical focus, and with small-aperture wide angle lenses.
Nothing is as easy as composing and focusing with a 300mm/f:4.5 on the 5x7", but try a 90mm/f:8.0 on the same camera and I ned something else.
So I always carry a black T-shirt. Mine's a Levis, it is particularly "dense". Besides, it was on sale...
I have rarely had any reason to complain about the heat inside the T-shitr. But that's probably because I live in Norway