Varnusz covers this in Play the Caro-Kann (Pergamon, 1982). The only illustrative game he gives in full for c3/Bd3/Qc2 is Forgacs-Duras, St Petersburg, 1909 (0-1, 26), but he also mentions in the notes various other Black wins such as Asztalos-Nomzowitsch (Bled, 1931) and draws.

Regarding ...h6/g6/Kh8, he gives ...g6 as the main line, concluding "It would appear at present Black has satisfactory resources to counter the White attack, though he must clearly proceed with caution." Of ...Kh8 (which he marks as '!') he says "This logical response has been neglected in recent years. Unlike ...g6 or ...h6, however, it does not weaken the Black king position." and (after 10 Be3 Nd7 11 0-0-0 Nf8) "If we compare this position to 9...g6 where White responds with h4, or 9...h6 where he follows up the attack with g4, it can be seen that Black's defensive position is much more comfortable."

I hope this has been helpful.

Today I had a quick look at this line of the Caro-Kann (1.e4 c6 2.d4 d5 3.Nc3/Nd2 dxe4 4.Nxe4 Nf6 5.Nxf6 exf6) and think this line could be an interesting surprise variation. However when searching for annotated games in my databases I found that most of the analysed games were White wins. Would anyone be able to suggest some model Black wins? In the Bd3/c3/Qc2 lines, is it better for Black to play ...h6, ...g6 or ...Kh8, and why?