I would start with the engine mount as this is a known cause of these vibrations and the just really fall apart.
I think the trans mounts for a pro are in the 2 hour range to do. There is a bit of stuff to pull to get to them and then wiggle them out. There are only 4 bolts that hold them in!
Here's a pic of the mounts:
1st Boxster 7th Porsche, we now have 4 in the family