For those who have disassembled the structural rear bumper:

Looking at the center of the aluminum extrusion, behind the license plate mount, there is a female threaded hole for the tow bar.

On either side of this hole, there are yellow plated bolts which appear to connect the aluminum extrusion to the structural (steel?) base behind.

Can these bolts be removed and used to attach a support plate without something behind falling apart? Are they threaded into a retained nut or a threaded portion of the sub-base?

I have looked at the shop manuals and can't see how these bolts are mated, or what the purpose is.

Any help appreciated.