I stumbled on two good SP custom maps for BiA Rth30:
A mission set near Bastogne (no snow, tho). Baker and his squad have to conquer a radio bunker. A very well made map. With a little bit of polish, it won’t be out of place among the vanilla maps.
A map with a good athmosphere. The objective is simple: conquer the farm.
It’s not properly finished. Once you capture the farm, the mission doesn’t end. But the level design is pretty good.