If when you put the lense in the indentation its flush with the bumper, I would stick them in, if you cut out the indentation you will need some sort of bracket behind, also you will have to seal around the lense or you will have dirty water running down the bumper from the rain etc. from behind, if you know what I mean.
__________________ VELVET BLUE UK INDIVIDUAL , IM THE LAST
UNITED WE STAND DIVIDED WE FALL
I stepped in a plate of Pasta the other day - now I have to worry about my Carbonara footprint!