C40 or C50
I can get fenders on a C-40 but a Cross frame might be easier. I am sure that Colnago makes frames designed for mounting fenders but it won't likely be featured on their web page or in their catalogues.
I'd pick a C-40 as the best candidate but they don't make them and a C-50 would be fabulous too.
Do you have a friend that speaks Italian? email them.