I don't know much about this, but...
I'm under the impression a smoker gets at least as hot as a dehydrator.(150+) I was thinking hotter, but I am not sure.
There are not many soft plastics that can take that kind of heat without degrading into the food. Silicone being an obvious exception, although relatively expensive.
I have had smoked sausage, and it was probably in synthetic casings, I just never thought of it before. Jerky sits on plastic in my dehydrator, but it is not a pliable plastic like a sausage casing.