Hello BESTGLIDESPEED
According to
ICAO Annex 14 variing pilot eye heights are an issue with VASIS but not with PAPI.
For VASIS the note after ICAO Annex 14 no 5.3.5.9 says:
"If increased eye height at the threshold is required (to provide adequate wheel clearance), then the approaches may be flown with one or more fly-down lights visible."
For PAPI there is no parallel provision. In Annex 14 Figure 5-18 it just says:
"Where a PAPI or APAPI is installed on a runway equipped with an ILS and/or MLS, the distance D1 [threshold to PAPI lights] shall be calculated to provide the optimum compatibility between the visual and nonvisual aids for the range of eye-to-antenna heights of the aeroplanes regularly using the runway. The distance shall be equal to that between the threshold and the effective origin of the ILS glide path or MLS minimum glide path, as appropriate, plus a correction factor for the variation of eye-to-antenna heights of the aeroplanes concerned."
I hope this will help you. Good luck
hvogt