Think he probably had a mid pair at best so obviously wasn't going all in, but is there any way I could have squeezed a few more chips out of him? Would a small cbet on the flop have been better? Or a slightly smaller river bet?
Don't slowplay, just Bet/Bet/Bet.
You don't want to see exactly those spots where they Check behind and you miss maybe even value. You are OOP, it will be hard to extract value for you.