Effective stacks are 100bb.

Besides the obvious adjustment of tightening up considerably, what other specifics may I be missing? It was a frustrating session during which I didn't pick up many big hands whenever he put 20bb in and my red line probably resembled a cliff.

1. Is there any merit to ever flatting the 3bets? He's not as crazy postflop. I saw him cbet flop and then shut down a couple times.
2. He has also 3bet/folded. In that case, how often should we be 4bet shoving light?
3. In addition to tightening up, should I be opening to 2-2.5x instead of my standard 3x, so that when I do fold to his 3bets I lose less? He's not an idiot and would probably notice if I only opened hands I was willing to jam over his 3bets with.

min raise when you open, unless ofc you have a monster (he isn't ever going to adjust) and find a new table.

once you get 33BB in its time to ship it. I'd wait for a decent hand and then raise over the top with the intention to get it all in. You have to be prepared to gamble in this case. AK, AQ, pocket pairs are all fair game. If its a ring game chances are someone else will eventually play sheriff.

I would tighten up in preparation for the 3bets, widen 4bet range and either only 4bet or fold when OOP.

No way. These are the type of whales we dream of. He is asking to be stacked, and we are racing with the other regs around the table to stack him first.

Agreed, I'm opening tighter, 4betting wider and taking the free 20bb

I think it depends on what "constantly" really means.

If you open to 3bb and villain is not in the blinds then he is trying to steal a 4.5bb pot by sticking in 20bb. Villain's bluffs need to work around 80% of the time to be profitable and the onus of defending against him doesn't fall solely on you because the blinds or other players left to act will sometimes wake up with a hand strong enough to stack him.

So even if you fold 75% of the time and ship the other 25% you should be printing money on this table without making any adjustments to your opening range.

Now if you simply stop opening hands that you know you aren't going to be shipping then you stop bleeding money by folding to his 3bets and you probably get him to stack off a lot lighter than he should because you are shipping on him 100% of the time.

Like the others said you need to be prepared to gamble more with this type of player. Also sounds like your tilting a bit. Just be patient and wait for a spot to take his stack.

I agree these type of players cause me to shutdown and I can lose my head a bit. Then I see a nit stack him with top pair and I think "that should of been me stacking him..."