first, what's the vehicle that you're looking to install them on? (i.e. a picture would be helpful)
i personally would not mount anything on the rear bumper; there are some people that install surface mounts on the rear bumpers, but i think that they are very likely to get damaged (whether the vehicle operator backs into something or someone else hits the vehicle). I'd def. go with a pair of linz6 on an LP bracket, and if u want vertexes, consider them on in the reverse light housing.