So I have a few rookie questions about tarp fabrics. What minimum requirements must a tarp fabric meet (other than waterproof)? Is ripstop necessary?

I ask this because I am curious what would happen if I made a tarp out of something like regular ol' polyester fabric and treated it with a make your own sil? Would the resulting "thing" shred the first time it was pitched?, at the first mild gust of wind?, or would it be usable for any decent amount of time? Or maybe is there something that can be done to normal fabrics to ripstop-ize it?

I've heard of people making "practice" tarps out of polyester to hone their sewing skills prior to operating on their high $ fabric, but has anyone ever used their "practice" one for real?

Last question... Am I crazy?