Ben, the file
110403_truk_l12_jgs_itrf05_04apr11_6138
is the precise trajectory of the antenna on the top of Kyle's vehicle
for the ramp survey.  Word 4 is latitude, word 5 is longitude, and word 6
is height of the antenna's phase center above the ellipsoid.

To reduce this data to the height of the ramp, subtract 1.809 m from word 6, 
and you'll have a pretty precise topo database of the ramp. 1.809 m is the
measured height of the antenna's (assumed) phase center from the surface.