NL 20 river.. should bluff?

I think folding or 3betting preflop (depending on his tendencies) would be better. With flatting you will not hit flop very often, but have some reverse implied odds due to your kicker.
Do you have postflop stats about villains? How much he cbets, secondbarrels, WtSD, etc. ? You can float him on this board with your backdoors+overcard, but it's a better play if you know he is a good target for it.
The turn is a bad card for barrel, but he still fires, you are not ahead here most of the time, and don't have the odds to call.
I dont like the river bluff very much, he can ch/call here with a lot of PPs.

Hello asimos,

Welcome to the English NL Hand Evaluation Forum! Hopefully we will see more hands from you in the future. I hope that with our help you can improve your play and as well move up the limits. We will be waiting for the next hands and till that good luck on tables!

Preflop: You have even people behind you who could easily be squeeze-happy. Therefore already not a huge fan of flatting and neither don't know much about opponents postflop play which you of course didn't point out. Cause without his postflop tendency difficult to understand how you will manage to play profitable your hand.

As played
Flop: Well, if you flat-called preflop then you should also fight back such boards. Especially when you have backdoor draws yourself and maybe even overcard out. Why do you float? What's his CB flop/turn?

As played
Turn: Not a huge fan of calling here while you will never even know how good your odds are. That's also why you should rather raise the flop and might even get a free river card if he plays passively on the flop and of course fold equity right on the flop.

As played
River: Don't like it without even knowing how much he goes to showdown. Rather just Check behind and be even happy that your Ace high is ahead. Difficult to see your play be very profitable. What you trying to represent?

Best Regards.