I think you'll end up ruining your fender and regret it. Why not check out Arlen Ness fiberglass fenders? They are on eBay all the time fairly cheap. There is another company that makes them that are cheaper but I can't remember the name. Keep your stock stuff and modify aftermarket. I usually just do a search of "Chopper fenders" or just fenders under motorcycle parts.
Personally, if I had a Classic, the frt fender would come off all together. Like this bike. My favorite 900:
YouTube - bobber vulcan 900