It's time to re-bed the stanchions and I'm wondering what's on the other end of the bolts that hold the stanchion plates down? I can't see what's there without cutting the plastic headliner (no carpet or inspection hatches that I can see). Is there a molded-in backing plate? Nuts? Can I back the bolts out, put some butyl down and put the bolt back in, or will I hear the nut drop off and disappear into the bilge, never to be seen again?