Am I missing the part about the 50ft obstacle or does it not exist?
Oh, it exists, all right:
3. Considers the wind conditions, landing surface, obstructions (emphasis added), and selects the most suitable touchdown point.
It's up to the DPE to tell you whether an (imaginary) obstruction exists, and then it's up to you to clear it. If the DPE doesn't specify, you should tell him or her you're assuming a 50 foot obstruction at the threshold. If the examiner wishes you to do something else, he or she will say so.
_________________The opinions expressed in this post are those of one CFI, and do not necessarily represent the position of the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS
AvSport of Lock Haven