Yeah, I was thinking of something to just suck in cool air at one end, where there's nice shade, while another one pushes hot air out the other end, so it's hopefully bearable, but looks like it may be back to the drawing board
Hession cloth hung over window openings set up with a dripper to keep it wet [ AKA Koolgardie safe style ] and a recovery tray to recycle the water ... mount a fan on the inside of one or more of the open windows to help draw air in ..
Two big as you can get thermo fans [ wreckers / dump / ebay ] rigged up via battery and solar panel venting up in the roof to vent heat out, if you have a ceiling ad large screened vents to the eaves .. My neighbour did this and said he got roughly 5 > 9* deg C cooler
difference in his roof space ..
If water IE: Stand alone for the shed > tank water.. Rig a solar powered pump to run a couple of soaker hoses over the roof and cycle it back through the tank .