Heat?

Atticfoilinsulation.com on youtube.

If you want to go ultra cheap, then solar emergency blankets.

It's all about radiant heat.

Imagine you're a convict escaping a prison, and each guardtower spotlight is pointing at you.

Radiant heat is the same, except each and every surface you see is a spotlight. Think FLIR IR camera. All that glowing is light, and if that light falls on you, you're being heated by radiant heat, even from the roof.

That AC will do little to nothing for you. AC cools air. And for that air to cool you, that air has to physically get to you to cool you down. And it looks like an actual barn that is leaky.

It's just like a campfire. All the heat you feel, is actually radiant heat. You feel no convective heat, unless the smoke blows on you.

I did this with a sunroom, and I went from stifling, stuffy hot, to completely comfortable, full pants/shirt, with no windows open during the summer. Sure the room was 90f, but it was surprisingly easy to live in.

I put it in behind window roller blinds.

The blinds stopped being hot and soft from the heat.