I thought I would chime in on this....
I recently did this modification to my trailer for my new 2021 Z20. Drilling out the rivets is easy, even easier if the boat is off the trailer but it can be done even though the boat can interfere a bit drilling out the inside rivets. I used the same self adhesive rubber diamond plate pads that Pat used. Cut them exactly in half. Before you do that line up the pieces so the diamond pattern matches at each edge. Not a big deal but I'm a bit anal about that kind of thing. I removed the center fender bolt, and cleaned the top of each fender with some windex type stuff and aligned the pads where I wanted them and stuck em down. With an exacto knife cut out the small bolt hole and re-installed the bolt. Cut around the outside edge of the bolt head so it tightened down against the top of the fender and not on top of the rubber pad. If you don't do that the pad will buckle around the bolt head.
Everything looked great. The next day, I took a look at it and noticed that the rubber pads were releasing from the fender surface, not good. These pads just don't have the adhesive strength we need. So I went to plan B.
Before I removed the pads, using painters tape, I taped off around the pads being careful to get the tape right up against the edge of each pad all the way around. Also taped on top of the carpeted board and extended out at least 3" outside of the pads. I then removed each pad keeping tract of which one went where. I noticed that the adhesive on the back of the pads is quite easy to peel off. So with a little work I peeled off all of the adhesive on all three pieces. Some took a little more work that the other, but when finished all were completely clean. I then sprayed each with 3M 90 adhesive as the directions said. Also sprayed the area on top of the fender inside the tape. This spray adhesive is fairly easy to get it where you want it as it applies in a web pattern, but the more tape you have outside of the area the better. It is important to let this adhesive tack-up for a minute or two which I did.
I then placed each mat back on top of the fender in the exact same place it was before. Immediately removed the tape when I was happy with the placement. Repeated this on the other side.
They are really on there now, no sign of adhesive release and I dumped them in the lake yesterday with no ill effects yet.
Pad No adhesive.jpgFender2.jpgFender.jpg