If V is mostly folding to your bets as the description says, I'd just fold. It doesn't sound like you'd get paid off if you hit the flush. You're calling $12 into a $38 pot, so he's denying you direct odds. You're OOP. The board is paired. If the spade comes on the turn and you bet, V is probably folding (unless you're giving him odds to call for a full house). The only way I'd call is you think V is capable of raising with a lesser flush draw.
If he often bets the turn strong (that is, half pot or more), I'm folding this here. If he often checks the turn or bets it too weak, I'll call and see what develops. My default is a fold (some rio, OOP makes it harder to get payed, OOP makes it easier for him to get payed, OOP makes it easier for him to bluff us, etc.)
I'm a huge position nit. This is one of those spots where I'll just fold. All of our options suck because we are OOP.
I like the turn check. We have a hand with some okay/weak SDV that won't hold up well in a big pot. We may as well pot control, and letting a street check through is fine for both our SDV and our draw. It may also induce continuation bluffs from draws we dominate (although this may just be theorizing), so overall I think checking is the best way to play the turn.
The river is interesting. Now, he can have a lot of stuff here. But if he's straightforward and passive, he won't bluff his missed draws too much. So I make a solid value bet that can look like a bluff: $40... or, if he's the self-leveling type, $50. If he has a pair of 7 or 88-KK, he will have an attractive hand to bluff catch us with, and there are missed draws for an excuse. The large bet sizing will make him more scared to bluff over the top with whiffed draws, so we can easily fold if he raises.
If he's just weak and has trouble calling big bets we'll just bet whatever we think he'll call. Most villains will call $35 here. It's just not a big sounding bet.
I dunno. We hopefully have a feel for how he will react to these bets. From your description it sounds like $35 might be better.