Some folks have had to put a ratchet strap on the structure and pull those two bolts together. Or if you have a rear suspension support bar, like the techno brace, this provides additional support and keeps those two points together. You probably don't want to spend any more $$$, but this would be the perfect time to install one. I've got one, and the last time I had the sheet metal brace off it went back on easy
The first time I had the brace off it was pretty tough to get back on... I had to use a rubber mallet.
Porsche Boxster Rear Suspension Support and Pedro Bar - 986 / 987 (1997-08) - Pelican Parts Technical Article