Getting nearly 30 in that beast is an accomplishment in itself
I second testing the grill block with tape before hand. Prototyping different layouts is easier that way before going more permanent. Any opening in the front that doesn't lead directly to the rad should be smoothed over. Start taping over from the top and work your way down. If the temps get too high remove from the bottom and work your way up.
I hope you fold back those side view wings before getting on any highways...
Side skirts might work, if you drop the truck and get smaller tires; but that's beyond the baby steps along with the belly pan. But if you can get material cheap, get a set of lifting blocks to get under it safely which would make it easier.