Well, I'll tell you like a mom. If you work the horse, ride the horse, you care for and cool the horse. My daughter loved winter riding but yes her mare would get sweaty. She would rub her down really good and put a sweat sheet on her so she could dry and still be warm, mind you this horse was stabled until she was pretty dry also. THEN she would put on her weatherbeeter turn out balnket so she could remain warm and dry out completely. She would later go out if it was still sunny and reasonably comfortable out and brush all the matted hair up again then put her blanket back on.
In my humble opinion, horses are work as well as fun. If you ride you owe it to the horse to "mess with it." Clipping a saddle area will be too cold for any horse.
I copy your first sentence "I need a partial clip that I can do on my big horse when I work her in winter. I can blanket her if I need to but I dont want to mess with it."
Not trying to be mean here ok, but too often the horse suffers for the riders pleasure. I have lots of winter riding stuff for horses if you are interested. PM me.