i used to have the underbody neons on one of my old cars and they held up pretty good, they did eventually break though, but that was only because a big box came flying out of a redneck pickup truck infront of me and i didnt have time to swerve, so i just had to run over it and it shattered the front bumper neons.
i dont think you have to worry about speedbumps as long as you take it slow around them, but, do worry about debris in the roads!!
BTW- i think pink neons would be great! but thats just my opinion