HJ is unknown but expect to not be a regular since I had no hands on him.

CO is a regular and I have 1.5k hands on him. His VPIP/PFR/3bet = 20/16/7.5.

From CO he 3bets 6.5% (78 occurences) and cold calls 7%.

Postflop his AFq by street is 49/28/32

WTSD 21%, W$SD 62%.

His Fv3bet is 62%. This made me think 3betting could be an option but since HJ is more likely a fishy player I think I get called in both spots way too often.

Hero stats (probably image vs CO): 21/18/8, 40/30/25 street by street AFq, 15% donkbet overall, 25% WTSD, 55% W$SD. Let me know if you need anything extra.

Dry board, backdoor flush. I usually expect people to be more honest in multiway pots. It looks like a good hand to have in my leading range. Given the HJ assumption that he is more on the fishier side I would definitely like Qx, possibly sets as well for value since I expect to get in more money this way vs HJ when he has a showdown value hand. When CO calls I expect him to have Qx, possibly slowplayed sets as top of his range. For medium and weaker part I expect A4s, A3 with backdoor flush, A5 with BDFD midpairs.

Turning the backdoor flushdraw on a card that makes middle pairs look weaker I think we can profitably bluff here, especially given his low WTSD, he should be more inclined to make folds, not calls with medium strength hands.

To bluff or not to bluff? This specific hand is one thing but I'm thinking general range construction here. What would you expect Hero's value range to be here when he bets from villain's perspective and what bluff range? What would you value bet in Hero's spot? Would you check/call anything? In Villain's spot, what would the bottom of your calling range here be?