i suggest getting some Sticky Mickeys 18" Tape, or take the tailgate to the local sign shop and have them apply a coat of transfer tape over the tailgate. Cut out the areas that need to stay covered with exact o knife. paint the body color, Peel masking and clear.
Second option would be to get me at tattooyourtoys.com after the whole thing is body color, & I'll do the white for $50 bucks.
Gric