I have seen kits you can buy to flush mount your c5 tail lights.They are quite costly.I went to the hardware store today and spent 15$ on 8 longer screws,weather stripping and small circle velcro pads and 1 foot of 1/4 inch fuel line.I took off the tail lights and the cleaned the area out.Put the weather stripping around the lights and then cutting the fuel line into 1 inch sections and putting the screws through them and putting the lights back into the car.It's that easy and the results are AWESOME.
Hope this helps anyone who ever wanted to do this.
The photos are in the photo gallery.Enjoy.