Without seeing the actual metal underneath everything it is hard to tell.  I have a love/hate relationship with POR-15. It isn't the tough as powder coat they claim, but it does OK.  I've used their matte that is like a thin fiberglass sheet with POR-15 and had decent results. I'll post a few picture of before and after with my Studebaker Daytona.

Before, sand blasted, POR-15 with Matte. While it is your choice/risk I felt the floors saw no more weight than the legs/feet resting on them. Six years later it looks the same.  It won't fly in show car circles, but I'm pushing 60 and only have so many viable years left.  I did weld new metal into my passenger front on the Pinto (last picture) but the Uni-Frame rail attaches there and needed the strength. The Studebaker is a frame car.