Hello,
For my side I have just tested the Guy's tip, with PCLP V 5.41 et Dongle O² V 3.1 (Sillage racing track), with 2 x ghosts and 1 x normal car and it works OK.
I set precisely Ghost car speed and target chrono in ghosts update speed menu (ctrl +G).
I have only seen some little bugs :
-sometimes when the car goes out from pit line it takes time to reach the normal speed, car keeps its pit line low speed during a short time.
-in case of car goes out of slot and I put back car on the track I get a wrong best lap time which is shorter that normal time (impossible to reach). I set In Option ->Detection reject lap time under a value in accordance with my track but nevertheless it doen't work.