You can size the river to get worst to call pretty much 100% of the time. Even a winner at this stake will be calling way too much if you size river properly. I wouldn't take a showdown because his river c/r or c/f is going to tell us a tonne anyway. Also giving up obvious +eV bets for future eV is probably not going to be with it at a stake with such a massive player pool.

FYI I would call flop/turn/raise river if he bets small again, bet when checked to at any point. As played I would still bet river like 1/3 pot.