Turn donk vs possible check behind

Donk is not a great play because if you check/call and donk out on the turn, your range looks like quite polarized between strong hands and bluffs or weak hands that fold to a turnraise and why should you check/call and donk the Turn with K9? Makes not much sense. And BU is certainly betting Kx again and each Ax. If you picked the read that he's raising with a lot of just toppair hands, donk/3bet is great but if he doesn't raise A7 A8 A9 AT which is ok from his perspective, you lose value against Kx and Ax and you make him folding pocketpairs that he might have fired another bet with - against your gutshots like JT QJ QT.

And your play is way unbalanced as you'd continue passively with small toppairs and Kx type of hands. Checkraise Turn should become your default.