i would say get a slanted bed cover, it would still allow you to use a majority of the space back there. if you don't have the tow hooks on the front you can get a couple small pieces of plexiglass to put over the holes for them, as well as the fog lights to smooth out the air flow. also you could cover the top half of the grille opening with lexan (to keep the look clean), when you do that also go under the hood and fill any gaps that could allow air to flow around the radiator rather than through it.
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