It is better if you do place a piece of plastic behind the numbers as this aids to keep them there by the end of a days racing (due to the amount of rocks and sand etc).
If you are like OKE then I suppose that you don't have to worry about that because you're never behind someone! But then what about lapping people? ;)
Get a 1/2 mesh plate they look trick even if you can't tell the difference.
Oz, nice looking ride.
I should elaborate on how I did my plate. I placed the numbers on the top half of the plate, then I took a razor and cut them along the line above the mesh. I then placed the bottom half of the numbers on the mesh itself, aligning them with the top halfs. Works real well that way. I have seen some who just put the whole number on and it leaves a bad gap. I can see where that would be a problem.
lol, I kinda like my poseur plate and vented fender! :)