Was looking at 20 oz cavalry twill today. For a pair of trousers. Can't say that I care for the twill fabric itself, but it's damn solid stuff.
I think it might also bode well for a jacket, perhaps even a peacoat.
22 oz. cords aren't overly heavy in winter, but I have no experience with 20 oz twill.
Holland & Sherry offers both 20 oz. and 16 oz. corduroy and, I believe, moleskins. Supply your own tailor.
I've got cords in both weights but not the moleskins.
Samples on their site and for swatches contact Werner Topel at Beazeleys, their retail outlet also on the site.