So Plan B is to use the cutout from the bottom of the cowl to form a smaller blister. I measured the distance the "flap" of material needed to be off the cowl, and used a piece of clay to hold that angle, along with a piece of duct tape to hold the aft end in place.
Then I glassed 1/2 the blister, making an aerodynamic slope with the glass.
Tomorrow I'll glass the other half, and then finally the inside. Then it's more filler and sanding.