PSA: My balcony tomatoes got fried in a single afternoon heat wave

Last Tuesday in Austin it hit 108 degrees and my full sun setup turned into a plant oven. I came home to find all 12 of my Roma seedlings completely wilted and the soil was bone dry even though I watered that morning. Everyone says more sun is always better, but I think we need to talk about shade cloth for extreme climates. Has anyone rigged up a cheap temporary shade solution for a south facing rail?