Trying to figure out the best way to seal holes...?

Since the previous owner turned the transom into Swiss cheese iv got a few unused bolt holes left over that i'm not going to use, i was planing on just using a nut n bolt with a washer on each side an 5200 in between but there is about 4 that i'm not going to use an i don't want it to look too tacky so i'm considering using some wax paper and JB weld putty, pinch off some JB weld roll it into a ball an fill in the holes an smash it flush then put wax paper on either side to support it untill it drys then just grind it flush, but the holes are a little over 1/4 inch and the alum is pretty thin so to make a nice patch job it'd be kinda hard.... Also i considered rivet's but if that's the case i might as well go with the bolts instead either way both are going to look like ***..

I have 2 on mine that I am going to fill but my motor will go over top of them. And I may use them in the future sometime so I think I am going to put stainless elevator bolts through from the outside with some marine silicone on the under side of the bolt heads to keep it water tight. That way I can remove them if need be.