Try some chewing gum. In your case, get some "BlackJack".

 

You mean like this .............. Most hardware stores have these displays for bolt covers ............ 3/8th's bolt

https://www.boltdepot.com/Chrome_bolt_covers.aspx

 

I'll assume you've never tried it. I've done complete engine Allen sets that way over the years to hide the rust. The silicone will pop right out if you need to reinstall a bolt or wrench.

 

http://www.boardtrackerharleyonline....ge_580440596=6

 

Got the black plastic plugs at local hardware store - check in the section with furniture caps & plugs. If that were mine, I'd put a painted carriage head bolt with a nut on the backside, if there's room. If not, I'd just run a short painted bolt in there. The black plastic plugs are great for filling the mirror bracket holes on a batwing fairing, though.

 

I've used the Ace hardware hole caps many times to cap off holes. But in this case on my bike, I'm going to simply buy SS set screws to use to finish the holes off. They won't be very noticeable as only the end will show, and wont have to worry about them rusting. And what can be seen just looks like a finished product. A drop of silicone or loctite to hold them in. But then, the black silicone idea sounds good too for that non noticable look

 

Pike nuts

 

Trying to figure that out as well lol. Glad the boards worked out for you!

 

If it were me I'd use a stainless buttonhead bolt