What would happen if you tapped a maple 30' up off the ground, and ran 3/16" tubing down to a bucket?

Would you get the full 29 inHg of natural vacuum through the whole season?

No pump needed.

if you really gain 5% sap production for every inch of vacuum, would you get 3x the sap compared to typical tap height?

Ignore the logistics of climbing that high to tap and pull them at the end of the season!