The bolts that come with the Curt hitch # C11289 that you mentioned go into weld nuts in the frame. If the bolts are spinning, this likely means the weld nuts have broken loose. This is not completely surprising for a 20 year old car. The frame rail is hollow, but I am not aware of any existing access point that would allow your to reach the back of the bolts. Even if you could get to them to remove the bolts, the weld nuts would have to be re attached to the inside of the frame in order... view full answer...
We don't publish the torque values because they can change over time, but the correct torque value for the Curt # C11289 class I hitch is listed in step # 3 of the installation instructions that I've linked for you. view full answer...