Silk is lightweight. You can get it at the same weight as ripstop nylon. You can also siliconize it to make it waterproof. Or you can oil it. You can also oil cotton to make it waterproof. For a sleeping bag that doesn't need to be waterproof, making a down bag with silk would be the same weight as one with a nylon shell. A tent isn't next to your skin, so you gain no tactile advantage from using all natural. Anyways, they make some pretty tight weave cotton that is approaching nylon weights, and would make a somewhat light shelter if used sparingly.


At any rate, check out this guy. He tries to only wear natural material.
Raven lore
_________________________
I've taken a vow of poverty. To annoy me, send money.