@DC Dart I had my machinist spray a really strong chassis black that he uses. Maybe some body guy types know but I know it wasn’t POR-15 or Rustoleum. The paint is extremely durable. I’ll message him and get the product name.
Yep you can literally buy paint called chassis black, use it on trucks etc, last resto i did the entire under side of car with it. Cleans up easily as well and very durable