Trunk Latch Receiver Bolts Loose, '02 Camry

Wonder if anyone has any experience with the bolts that hold the receiver in place, on to which the truch latch engages. Both bolts are loose on my '02 Camry, and neither will not tighten with a wrench. The loose bolts allows the receiver to move, sometimes not aligning with the trunk latch, resulting in the latch not engaging. Bolts can be viewed at:

Access to the back of the bolts is almost impossible. The back access is blocked by sheetmetal. There is an opening several inches from the bolts that might permit insertion of a special tool. I've been to the Toyota dealer twice (120 mi.s round trip) without success. A third trip is scheduled to discuss with one of the wizards who has been on vacation. The dealer has two Toyota wizards, plus support staff who are baffled why they can't tighten the bolts.

Does anyone have any experience to actually know what locks these bolts? Is it a lock nut (what kind), lock washer, threaded sheetmetal, or what ever?

Secondly, is a special tool needed to hold whatever might behind the bolts?

I note that older Camry's seem to have a similar detail.

I'm counting on the wisdom of this NG to offer a better solution than what the dealer has offered.

Thanks in advance, and Cheers! Jim