Jason I'm wondering about why the POR 15 should be topcoated. I went to their website
POR-15 Inc. and it says that if the painted area is going to be exposed to sunlight, then by all means, there should be a topcoat because the UV rays will break down the paint. But underneath the carpet and the rear deck will be hidden from the sun and should be okay. I'm also going to use it on my inner rocker panels when I get to that point. Cheers!