The 3-bet thing has been beat to death, so I'm not going to address it. I want to clarify what I think is a GREAT line here that has only been touched on - the flat/raise flop.
If you flat his PFR and get heads up, or EVEN three way is good since you say the table dynamic is that no one is really playing back at him, my plan would be to raise the flop most of the time!
You state multiple times that he is c-betting every flop, so why not just let him put some bad money in and raise him off almost everything that whiffs?
Here is how I see the pot going the 50+% of the time I DON'T 3-bet:
Flat pre pot is $39 after rake.
V c-bets $20-30 (note someone said V will pot c-bet, I doubt this big time as most V's like this have no sense of pot/bet sizing).
Pot is ~$65, we raise to ~$70 (I'd go with 2.5x whatever he bets).
He folds all whiffs and even some hands that are ahead.
He shoves anything that is a decent hand and we can fold losing only $80-90, almost the same amount we lose if we 3-bet and give up when the pot is re-popped by someone or he shoves.
IF you get another caller this line is even better AND looks stronger.
Pot is $59 OTF, he bets $20, we raise to $60 and win $60!!!
I'm not discounting 3-betting, but vs this player I think this line is great (I think it looks WAY stronger to fish) since it really makes him define his hand and we risk almost the same amount. He will wake up with a hand once in a while, and I don't want to pay him off for $200 with K high. Also, you keep from getting into a pissing match with a guy who is there just to try and out-piss everyone by calling 3-bets and shoves with any pair.
FWIW I had KQ at a table with a similar V who was showing a lot of crazy plays (even showed when he woke up with KK), and I called a raise on the button with KQ. He c-bet a T84r flop and the other guy in the hand folded, I thought about raising and chickened out, he showed 32o.
Would have won $50 after I looked really strong raising vs a fish!