Why would villain be checking flop often?

Agree with DD. Although i am not a very good player, only betting my strong hands here esp if multitabling. Check to keep my low equity; not cbetting just because Hero checked.

OP said he would fold this to a CO open

OP seriously needs to work on his pre flop play

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This.

I play hand same as you (with exception that bb defense is trivially standard) but could be convinced that river check is overly nitty. I do feel like you get called by almost any low on this river because of your flop cr on that board texture and run out+turn action. Your hand looks high and he just calls and prays you have no low and his rags can take it. That's an argument for checking but not the end of the story.

He's probably almost never gonna bluff this river. That's an argument for betting.

He's probly not betting aces up cuz ur hand has plenty of broadway that got scared of the flush in it. That's an argument for betting.

He might not b paying much attention and doesn't know u so will he call with aces up? If yes, that's an argument for betting.

All these value factors have to be weighted against those times when he calls with a low, making your river bet worth zero and those times when he raises/calls you and you call/show down and lose. It's a math problem.

Pro poker tools can help with this. http://www.propokertools.com/simulations. Plug in ranges for villain. You can plug in percentages and narrow the ranges as you go. I don't use this tool enough and may delve in with this hand but no guarantees. Anyone with any other range calculator ideas better than pro poker tools would be appreciated. Anyone with tips or caveats about pro poker tools would be appreciated. I'm thinking about preflop percentages specifically. Those are pretty straightforward in Holdem but not sure about o8. For example, I can see how a naked pair of jj could be overvalued in an o8 simulator based on hot cold equity where playability could b a nightmare.

Finally, death donkey flop donk. When do we check raise flops? I feel like if we donk this flop we donk as semibluff too. I have to say the idea of donking here feels like a good idea but I'm wondering how you incorporate it into an overall strategy.

Well as you said I would donk some other types of hands here as well. We should still have some hands to checkraise, on this board I would prefer our hand to be a bit stronger. And we should tend to CR when we are strong on boards that favor the raisers perceived range (for instance - wheel card flops)

Ok, so for example we checkraise flopped sets on this board for value. What bluffs/semibluffs do we checkraise then? cuz it seems like we donk those if we donk bottom two.

This is coming from someone who checkraises bottom two on this board, in part, because I'm checkraise semibluffing a decent amount. Maybe too much. But part of me feels like if I don't then my checkraises will be too value heavy.

i like the simple bet flop and bet river. he is a good player dont get cute with check raises here. and being a good player he is more likely to pay you off.

Where can one find a 75/150 game? please

Don't take this the wrong way but I am trying to be helpful by saying this. You are probably playing too high for your skill level with these questions. Poker fundamentals are missing here.

he did say he was new to o/8 and it was part of a mix. most mix players have a few weak games.
and 75/150 is a higher stakes game but isnt so high as to find the best players sitting there.

I appreciate everyone's responses.

Regarding preflop play: when I first started learning LO8, a lot of material strongly stressed tight is right. I even heard that VPIP should be tighter than in LHE. I can see that this is still a trivial call without a second thought, given that I'm in the big blind (pot odds). This is where my fixed limit inexperience shows most, I think.

Regarding flop check-raise play: At the time, I felt that he would be CBetting this flop nearly 100% of the time. However, I can see how it's kind of a disaster if he doesn't CBet, and I will occasionally be setting myself up in rough spots if he is only CBetting hands that have decent potential to beat me.
Could you elaborate? I understand that some of my O8 fundamentals may be weak, but I'd definitely like to know what general poker fundamentals you think I may be missing.

I appreciate the honesty, but, while I think I'm a dog against the stronger players in this game, the weaker players make some major mistakes that I think will result in me being at least a winning player. Plus, it's very good experience. Gotta learn these games somewhere, and this isn't crazy high stakes. If I have a really rough downswing, I'll just stick with 5/5 PLO to rebuild my bankroll while I continue to study.

I have to think the poker fundamentals he is referring to is understanding hand strength and pot odds when playing from the big blind.

Giving any thought to folding this hand in the BB to a single raise from any position is a major mistake. It is hard to see how you could be a winning player in this stakes game when you are giving away this much equity.

The older written material on O8 was generally very deficient when it came to play in the big blind. The standard attitude here has pretty much evolved from "BB play in O8 is a still a big mystery...play what feels right" to "play almost everything". But even given the old-school attitude, if folding AJT5ss "feels right", something is off about your feel for the game.

The highest stakes I have played are 50-100, but I believe you must continue to bet the river. The likelihood he has some sort of low is higher than the likelihood of your high being beaten. You must try to force the low to fold and not get to a free showdown. You are ahead of his AAxx hands, you are also ahead of his suited ace baby raising hands. Don't let him show down a crappy low for free.