Oh and also the flop/turn bets are likely more important than the river bets here, if we bet more on the flop we can exponentially bet bigger on later streets without it "looking" like it's too big of a bet.
what i mean by this is lets say we bet 8k on flop, if he calls which he will if he has a strong second best hand, then the pot on the turn is now..
26k.
We can now bet 22k on the turn and if he calls we are now in a position to jam the river and go for his whole stack. This might seem a bit greedy, but how many times do you see randoms or fish folding when they hit "strong" pairs? the answer is rarely, when they fold they are folding because they likely were not planning on calling much more anyways.
the other thing is if he does have a draw, and we bet so small, we are just letting him get there really cheaply, this is bad not only for the chance of letting him catch up for a good price which means he makes less of a mistake and we make less money in theory, but also because we lose alot of value for all those draws that would have paid alot more to see that final river card only to miss.
Sorry for the long winded answer here, but this is a very basic situation i think which a ton of players get wrong (including myself in the past) so hopefully this all makes sense. Vs randoms or fish, bet really big, like you cannot bet big enough most of the time, the amounts of times i've bet over pot on flop/turn/river and stacked fish is incredible, give it a shot you might be suprised at what they are willing to get their stacks in with..