That sounds like a good plan, putting back the same stuff you had in the winter.During winter I had tons of hale bales and everything winter proofed but since we took everything put it seems to have gotten worse as it was more calm in the winter. So I think were going to add in the same stuff we had during winter and try to make it cooler for the summer hopefully.
To keep it cooler for summer, leave off anything covering the walls, especially up high (because heat rises: so they could have hay bales at ground level, but air movement above, and probably stay cool enough.)