I just finished welding in some new metal where the support rails are for the two front seats. Everything else was solid so I did my best to get the rust off then I sprayed on the Rustoleum bedliner inside.

My question is this, on the underside I have much more surface rust at the lap joints of every panel. My original though was to wire brush the rust away then undercoat it. Then I started thinking, what are the merits of bedlining when I'm rather positive the rust will just come back under the liner. Should I not spray the liner and just use paint so I can see it faster? Before, I wire brushed it and sprayed on white paint to seal it. I lucked out because the white paint showed the rust very quickly.

I'm just curious what the opinions are on this. I do have a pint of POR 15 as well which isn't enough to cover everything but it might be a good "side by side" comparison to see how it works. Thoughts?