The corvette isn't an aerodynamically slick car, never has been, and if it is now, it hasn't been until recently. The main focus is on downforce and cooling.
this is supposedly the underside of your car. This is likely going to be the focus of your efforts, as the top is pretty well smoothed.
you want this as smooth as possible, ideally a solid sheet of aluminum or coroplast supported by standoffs. if a solid sheet isn't practical, getting as close as possible to the lowest hanging objects (exhaust, cross members, ect...) supported by standoffs.