the correct way to smooth it is to extend it, basically by welding a metal plate over where the standard lights are, hence you dont need to change the standard ones if that makes sense
i did weld a plate in mate, but the standard lights wouldnt have fitted under the plate. these are quite slimmer.. once i cut a hole for them they will sink in nicely, i left gaps in the steel for them and then just reinforced it with fibreglass from inside the boot before i fillered.
as you can see, its not finished yet, if you look at the two top corners they are a different shape.. it was getting dark and i knew i had to use the car the next day so a lick of paint just to stop it rusting was needed.
