You've just reminded me that there was another quirk I wanted to mention...
For my first couple of installs (I tweak & reinstall quite a lot

), the first option (for P3D native safedock) was inop. - with it selected there was no safedock on any stand. Eventually I switched to the FSX (only) option, and they appeared & functioned without problem.
Actually on a subsequent install, I have the P3D native ones working. I have my suspicions that there was something not quite right when the installer completes and launches the configuration tool. If I install Amsterdam first, I get warnings that P3D is running, and its config file isn't writable (both statements incorrect); but if I install Vienna first, then Amsterdam, there are no errors.
Anyway... How this relates to your problem, is that in selecting the FSX safedocks out of curiosity, I found them to be fully functional (in P3D 3.4.9.18400) - including left/right guidance. Perhaps that's an option that'll give your marshallers a rest?
Regards,
Rob.
(For the record, on my most recent install, the P3D native safedocks appear and function (though of course with only in/out guidance))