Plug the holes!....
Of course it will seal the holes. But are you willing to depend on the glue not coming back up?
I did a job on an Artic Cat 3 years ago, replacing the old mats. I did not plug the holes. It held up fine, looked really nice.
Then, one day she (a good girl friend owned it) called me and said the ski was half under water. She had been sitting on the rear of the ski with the bow pulled up to the bank, having a cool one chatting with friends.
I came down and drained the water out, then started looking for the way it got in. Those rivet holes sit within an inch of the edge of the turf. If that contact comes up slightly, around the edge, the chances of you getting water in the hull is very likely.
So, the idea of sealing these holes for 100% water tight seal is better than relying on glue (I use the 3M-90 Super Strength, it's a spray on, its not let me down yet!)..........:cheers: