truck bed liner in the trunk?
I would suggest using the Black can of 3M undercoating. The Rustoleum never dried! The 3M has a fine texture and is like a hard plastic once dried. The Rustoleum is smooth. Here is a shot of the fuel tank I did with the 3M and the bracket for the fuel pump and filter was done with the rustoleum. Again, the Rustoleum still hasn't dried!