We've done a field shelter to double as a lambing shed, and the design we got has foot long slats at the top of the back wall which faces into the wind. This not only stops (or tries to) it taking off in our Cairngorm gales but also means it has very good air circulation. It might be worth considering something similar?
We got ours made but you could DIY something similar, this is the one we had, second photo down shows a close up of the slats. It's amazing that hardly any rain etc comes in, we used upgraded dimensions of framing so it's quite deep, bit like a medieval house window!
Can't get the link to work but if you google saltire stables and then look at the picture gallery menu option then for field shelters the first few pics are of this design (altho we have boarding to ceiling on the walls too)