If it was my truck I'd either go with the rivets or the allens and call it a day. But that's pretty nice paint at least what we can see of it. Depending on your skills with body work, you could locktite some bolt stock in the threads a little below the surface, top with a tiny bit of bondo, and paint to match. If your really careful with the bondo you could probably get away without even having to sand it. If that's the case get some matching touch up paint at the auto parts store and just put a enough on with a little brush to cover the bondo. I think doing it like that you could get those spots to look like they were never there or pretty damn close to it. Realize though this idea comes from someone that isn't really a body guy.