Guillaume Dery
Why not please both the aesthetic side of you and the practical side?

On the one hand, bolt heads are ugly. On the other hand, you need to periodically get at them to adjust.

Nice decorative plates, be they of the black iron or brass variety , pinned in to cover the hole would answer both needs methings. This is nothing new as it has been around for covering bed bolts as long as bed bolts have been around. I have seen some that are a definite visual plus.

Not as pretty as making the hole dissapear but very pretty nonetheless and infinitely more practical.

Just my $0.02 (Canadian, I have no idea what that's worth down under)

Guillaume