imo, goal is to make the hand easier to play and not to allow your opponent to play perfectly against you.

i considered the call/donk non spade turn line also, i just thought that it doesn't really give you enough information, and makes it almost as hard to play. say you call flop, turn is like a red duece, you lead out, he raises..... your line looks so fishy that you might get raised by any two. say he calls, river is a spade ... now what? ... there are just a lot of difficult situations you are going to be in. the only way to avoid this, and to avoid letting your opponent play perfectly is to put the 3rd bet in on the flop.

the way you decided to play this hand allows you to win the least and lose the most. curious to see what other people think though.