Second pair no kicker/tons of backdoors/passive stealer; line?

[Leader]

Villain is a loose kind of passive 52/8/1 over 350. I haven't noticed anything interesting yet. It's pretty early in the session and I haven't done much so far.

15/30

Pre-flop: (6 players) Hero is BB with 5[img]/images/graemlins/club.gif[/img] 7[img]/images/graemlins/club.gif[/img]
3 folds, <font color="#cc0000">Button raises</font>, SB calls, Hero calls.

Flop: K[img]/images/graemlins/heart.gif[/img] 7[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/club.gif[/img] (6SB, 3 players)
SB checks, Hero checks, <font color="#cc0000">Button bets</font>, SB folds, Hero...

Maybe this is an easy spot for most people here I donno. There seem to be only three lines that are close to +EV.

c/c down unless the board becomes terrible
c/r/call the flop and fold the turn UI
c/r/call the flop and calldown unless the board is terrible

Seems like we have a marginal EV edge here at best vs. a 8%pfr even if we add some for the BT. If villain was agro postflop and not that smart, we could probably just calldown most boards and expect him to bet down enough. We might even c/r-calldown if he's bad enough. We don't want to raise and then fold against such a player because of his bluff frequency.

Against a passive guy, I'm not so sure this is the best strategy though. Seems like we'll be putting in a lot more bets against the strong part of his range while he checks behind his weaker hands. So c/r'ing gets another bet out of Ax and folds out overs to our pair either immediately or on the turn. It also seems a lot less likely that we will be 3-bet by a worse hand both because he's somewhat passive and because str8 draws aren't in his opening range. If we do take a c/r/call-c/f line, we're also protected from a decent amount of those bluffs by the fact that we'll be continuing on any 8-3 or club. Then, of course, we have to decide what to do with a river blank. Call if there's no heart hoping for a busted FD getting 9-1?

Thoughts on this? Maybe there's some line I'm missing or something.