Given the fact that you are up against a "giant lag" You could easily have the best hand on the turn, so I like your turn raise, I actually see this more as a protection raise than a semibluff raise. Im not sure I like your flop play, if youre gonna call the flop(which you certainly should) you are much better off investing an extra small bet and raising the flop to force out the SB, you could easily have the best hand on this flop so it is important to try to get this heads up as soon as possible, but if you believe that the SB would cold call the flop raise but would not cold call a turn raise, Then I really liked the way you played this hand. Also River check is standard.