What happened to that competent body man you mentioned earlier ?
Whoever you use, be prepared that the holes in your car may have to be enlarged to match up with the studs in that particular backlight frame. .
I say may, because I know of a situation where that was necessary.
Microplas took that into consideration on their frames, so I guess you could modify that frame of yours with the Microplas type adjustable studs...more or less an eye bolt running along a glassed in metal rod.