Good call! 30 definitely won't do the trick@tstrum For my area I need 50% or above, otherwise it won't do anything. I'm thinking you may need higher than 30%.
If it helps here is a post from Michael Hagedorn putting up a structure, at the end of the post is a pic of the 30% shade cloth and how much shade it provides. See if you think that's enough for what you want
https://crataegus.com/2015/09/16/building-a-metal-shadecloth-structure/