I just bought a Ranger 461VS that had some older electronics mounted on it in the past, and had a cleat removed in order to make room for a ladder. These had left some holes in the fiberglass that I couldn't bear to look at, so I came up with some ways to cover them up.
The old electronics holes:
The hole where the old retractable rope was:
First the electronics holes. I had an old plastic cutting board I had been saving for a long time because I knew I'd come up with a use for it. I started by making a template out of newspaper, then transferred that to the cutting board and cut it out with a hack saw. I sanded the edges smooth, and rounded off the corners to make room for the windshield. I measured and marked the locations of all the holes, drilled pilot holes, and counter sunk them ahead of time.
Then I screwed it into the boat, and using the 1.25" hole I had drilled in the cutting board as a guide, I widened the hole in the boat to match. 1" was going to be a tad small for all the cables I had to pass through there. After that, I unscrewed it from the boat, and hit it with 3 or 4 coats of gloss black spray paint. After it dried, I mounted the RAM ball by running bolts through the bottom counter sank so they sat flush on the bottom, and secured it to the top with acorn nuts. I then mountedit back on the boat with two rubber washers under each screw for both shock absorption and some small measure of waterproofing. After I ran the cables, I utilized some flexible 3/4" conduit I found at Auto Zone to make the wires look better.
The finished product:
For the hole back by the ladder, I decided to install a 1" RAM ball to mount my GoPro to. I found a 1" ball that is meant to mount to a motorcycle fluid reservoir. It has a cap screw running through the top of it and is meant to replace one of the screws in a brake fluid reservoir. I put a rubber washer under the RAM ball, topped that with another stainless steel washer that I hit with 3 coats of the gloss black spray paint, and put it over top of the hole. Then I put another washer and nut on it from underneath.
I don't think they necessarily count as clever lol, but they did help me not have to look at the holes anymore. Sorry for the sideways pics, they show up normal on my computer. I'm not sure why they're rotated here.