Let us know how this goes. I will be doing something similar myself!I wonder how the bumperettes are even taken apart, there are two bolts in the back and many screws at the bottom..
Anyways, I ordered those 2x3 rubber rectangular plugs from amazon:
* they will definitely need to be modified in some way.
I was too curious and they are very cheap!
I measured the opening and the pimple bracket as well:
Mo in [Quarantined] NJ