Hi Andy! I think it would work great, especially if it's the 60/40 cotton/poly cloth which I've found to be way better than cotton. I have worn BDU pants made from this fabric for years in extended desert, mountain and canoe country treks and have found it to be superior to 100% cotton in all respects: it breathes just as well, is just as safe around stoves and fires, dries much faster, and lasts a lot longer than comparable weight 100% cotton poplins or ripstops. Plus, such a jacket is much more affordable than a fancy anorak made from egyptian cotton!
Such a layer would, of course, be strictly a "dry cold" fabric though, as it will absorb water. My favorite winter shell is one of the "Fishtail" parkas (actually a 65% cotton/35% nylon fabric). It was cheap, has tons of room for layering underneath, good lower-thigh coverage, great handwarmer pockets, is designed for excellent freedom of movement, and is really easy to modify. Of course, when combined with my green wool army pants and my green Filson cap with the sheepskin earflaps, I'm often mistaken for an East German border guard...!
Cheers, and have fun!
