Poker Stars, $1/$2 No Limit Hold'em Cash, 6 Players
Poker Tools Powered By Holdem Manager - The Ultimate Poker Software Suite.

SB: $201 (100.5 bb)
Hero (BB): $312.95 (156.5 bb)
UTG: $324.21 (162.1 bb)
MP: $200 (100 bb)
CO: $209 (104.5 bb)
BTN: $200 (100 bb)

Preflop: Hero is BB with Qs Qd
UTG raises to $6, 4 folds, Hero calls $4

Flop: ($13) 4d Ah 9c (2 players)
Hero checks, UTG bets $6.33, Hero calls $6.33

Turn: ($25.66) Tc (2 players)
Hero checks, UTG bets $16.67, Hero folds

I don't have much hands on villain, but it says he's a tight opener on earlier position. We are also 150BB deep, so it felt that just cold calling seems better. Flop=Standard but the turn is a pretty awkward situation. I assumed that he's opening 18% from the UTG>checking some aces and midpairs OTF>Cbetting almost all unmade hands OTF. With that in mind I have 44% coming to the turn. However if villian is slightly aggresive I probably won't win this pot more than 20% of the time. If he bets with GS+ and AQ+ I have about 40% equity, but because of the fact he's very likely to bluff the river with his missed draws I am not able to call here. He will bet around 60% of the time. When he checks the turn I would have around 50% equity assuming he has trash, some midpairs and some Ax hands in his checking range. This result seems to negative comparing to my 44% equity coming to the turn.

How do you guys look at the idea of donking this hand on the turn, to realize more of the equity. And what for sizing should I use(I mostly bet around 35-40% when I decide to donk the turn)