We used 5/16 that they have at Lowe’s and a I think a million people have used. Ours hasn’t broke but there are a few places I feel like I could push through it, but why would one do that? Anger, slip and fall? It’s been good and we haven’t had issues.
You could do some thin ply behind or put in a lot of studs. I wish we had a few more studs. Only though because it would make hanging things easier in certain places.
Shiplap might not bend as well and is considerably heavier, which is also a concern. Still where we have studs 14 inches or so apart we have no issue leaning against it.
You may have issues with the cedar cracking though if you don’t use a brad nailer when you fasten it. Try it out of the van first and see if that’s an issue.
Cedar turns grey with age if you don’t seal it so be sure to do both sides before putting it up. Good luck!