You can't use pilot assessment if RVRs are below 150m. Minimum reported RVRs of 125m are required for the ENTIRE take off run which you won't have on a displaced threshold.
From our Part A (UK airline):
"Pilot assessment of TDZ RVR when practical always overrides the reported TDZ RVR or Met Visibility."
Hmmm. So it seems to be operator specific, as all these Part A references being quoted are approved by the regulator...