You might want to check out this argument by Clifford Will that clock synchronization isn't really…
You might want to check out this argument by Clifford Will that clock synchronization isn't really an issue with measuring anistropy of light. I.e., sychronization is an issue but irrelevant to the results of one-way experiments: https://journals.aps.org/prd/pdf/10.1103/PhysRevD.45.403