Looking good!
You could always paint the visible rivet heads black to blend in a bit.
Is your vent cover removable?? If so, id recommend fitting some very fine mesh in the vent to filter off larger particles as the last thing you want is touching the grass or going through the kitty litter (or more likely someone in front doing the same) meaning your car fills with a cloud a dirt or dust while youre still driving at speed!!! Also catches insects and other thrown up debris.
You then just clean the mesh every now and then.
Also dont forget the drain pipe. With a fine mesh you should still be able to drive with the vents open if hot and humid as the mesh will damp down the spray.
You could be really anal and use some foam behind the mesh to catch everything.