He is tight, not super aggressive. You say you flat, rather than 3 bet pre because its at the bottom of his range, maybe, maybe not. If you 3 bet he seems to be tight enough to fold many hands that your behind, small pairs etc.
Use your hud, or popup information. What is his ep PFR (1%? just fold pre)? I would imagine it is much lower than 7.5, if he raises that much ep, then he is going to fold to a 3 bet often I would imagine. Also use that info as well, fold to 3bet%. If its real low, and he calls, your probably in trouble. If its high, then he is going to fold too much not to 3bet with AQ, and many other hands if your not doing it too much.
Lose the 3 bet when your beat, rather than lose your stack. As played, ep PFR%, flop Cbet%, turn cbet%, river... When they keep on after they usually shut down it is time to worry. When they push after they usually shut down, its time to fold with TP SECOND KICKER, you put TPTK (I am folding that as well depending on the other numbers, not risking my stack when I am at best only going to tie). Another stat, I always look at pretty much no matter what type of player, and if I keep posting here I will keep saying it over and over again. WTSD%, W$SD%. Go look at this guys, the first is one low, the second one is high I bet. Someone like that, you don't want to be playing for stacks against with only a pair. Maybe a overpair, even then not really,and not every time. Think about it, the lower the WTSD% is, the stronger a hand you need when they want all the chips in the middle for the showdown.
Hope this helps with the problem you say your having with not being able to lay down TPTK hands, and helps you to be able to keep them when you should.