sanding metallic with 1000 to 1500 grit should be fine, the clears will give back the gloss and depth, epoxy clears yellow , so you don want that, urethane clears are the way to go, they will hold up well with nitro, ppg clears will hold 90 percent nitro, i am using slik and quick clears from axis coatings, a quart plus hardener runs 30 us dollars, ad some medium reducer for another 8 dollars and you are good to go