No idea what holes are in the front bumper tbh as my plates are still stuck on (sort of) the same as yours. Its a job to get round to once the Murple is done.
The holders don't last forever, but you can treat the plastic the same as you would rubber or plastic trim which extends its life considerably. Plus they are cheap. Buy two sets that you like and keep one in a cupboard for use in a few years when the first set fades