Poor Quality Chrome

You might have luck protecting the "chrome" spray paint with an acrylic (water based) clear. I find that on model cars even the old Testors silver enamel, airbrushed, and then baked to dry, and then cleared with something like a Tamiya acrylic looks pretty chrome-like and will not tarnish. How this will hold up in the real world (outdoors weather) is pretty much an unknown however.