Mine is a 7 inch flair, but the truck is now 1.5 foot wider in the front end. The wheels still stick out side the flair by 4.5 inches at mid travel. One thing to keep in mind is the stock fenders are crap and there is a real good chance they will not survive the mold process. Mine folded like paper at the bottom near the door. Have you done many molds? In by build thread I show some tricks on the flanging process. Just look closely at the pictures.

It would be nice if you flange the mold around the flair it's self, before doing the rest of the fender. This way you can make just a flair or complete fender and flair. It might be worth the extra day just to give your self the option. Then you can sell the flair as a bolt on option for stock fenders. It just makes the mold more versatile for you. You would have somthing like a 7 peace mold when done. Mine is 6 just for what would be 1 fender if it was stock. Next year it might be a full stock fiberglass cab out sides.