I would cover them with passenger floorboards, but that's because I sometimes pickup stranded motorists.

 

You can buy the black plastic caps from any HD store or Fastenal store. I bought mine form HD for .35 cents each.

 

I threw a set of the chrome passenger peg mounts from a street glide when I took off my pax floor boards.... Wont work if you want it gone entirely but it looks heaps better than the floor boards

 

The ACE plumbing dept has chrome push plugs that will fit it.

 

HD does have little black plastic plugs that go in there. Just look at bikes that come with solo seats in the showroom.

Me, I just put heavy grease in them.