Updated 5/28/2018:
Work continued today on the first table. In these first two photos, I attached a straight 10' poplar board to the wall on the studs. It is level and up against the bottom of the table.
I then screwed the table top to the poplar board with 3" drywall screws. Checking the table against the laser shows that we have a pretty level platform (given we are working with pine).
So far, so good.
George