It's been a while since I've updated my post here - mostly because my hood flapping issue seemed to get considerably better after I removed my hood deflector. That said, I have noticed it shaking here and there since, but not quite as violently as it did with that deflector.
I think I mentioned that my dealer claimed the latch couldn't be adjusted and instead played with the hood bumpers (which actually allows more air through the hood seam, since it increases the gap).
It was especially noticeable today after I got it washed and the hood was nice and shiny - so I decided to take matters into my own hands.
For anyone else who wants to do the same, it's actually quite easy to adjust the hood latch - and there is plenty of play in it, though mine was already pretty low from the factory. To do it, you just need to remove the radiator shroud (about a dozen clips, maybe a few more). Once that's off, there's just three bolts holding in the latch, right front and center - two to the left and one to the right of the hinge mechanism. Use a 12mm socket to loosen the bolts. Once they're a little loose, you'll notice that there's plenty of play in the latch. I lowered mine as much as I could and snugged up the bolts to test the fit. Once I was confident that everything aligned as it should (there is some left-right play as well), I torqued them down really well and replaced the shroud.
After that, the hood wouldn't close with the bumpers at their dealer-set position. So I screwed them up a bit into the hood (clockwise motion) and repeatedly tested to see how easily the hood would latch. As it sits right now, it requires a sizable slam. But that hood is absolutely not going anywhere - and I believe the gap is lessened greatly, which should hopefully reduce lift.