I used to have a 'kinderseat' in my '86 560SL, but took it out and made a new plywood platform with kit-supplied carpet, like OEM. I didn't have an original to compare to or get measurments from at the time, so I made up my own retaining clips at the front and copied the cut-outs from pictures.
Now, I have a friend with the original platform in his '85 380SL. Neither of us can figure out how the thing is fastened down. There's what look like 2 handhold cutouts at the front, like I made, but pulling on them doesn't budge the platform. Are there screws in there, or do you rip up the carpet to access the fasteners, or what?