Just a caution about softshells here in general they're not that windproof - rather less than wind shirts quite often. Especially not some of the Schoeller fabrics. Done on purpose and more than fine for most people on legs, maybe not here.
Depends on what style/weight of Craghoppers is involved here but they'll have had some wind resistance.
Something really thick like Haglofs Rugged pants perhaps? Paramo style stuff for winter is a good option but maybe not needed. As an extreme measure there's stuff like windstopper style trousers, but I'd guess shouldn't need it.
(Air permeability figures not always trivial to get, might have to badger people to get the data.).