The key is the following:I want to desist. But that would mean I need to toss all of the GPS evidence proven everyday in the trash.
GPS proves light is not isotropic in the ECEF frame everyday. Do you refute the mainstream evidence?
"So, what is the experimental basis of special relativity without MMX?"
Your way of dealing with this is intellectually fraudulent. A tendentious misinterpretation of MMX is taken to refute it plus hundreds of other experiments supporting SR.