If you accept the newly adjusted timeline for the Bosma truck to go north, then south and north again accompanied by the Yukon, then you would have to also adjust the time the Yukon passed earlier before parking in the field. This would fit. Now I think MS has been tailoring his testimony to fit evidence that's been accepted. However, just because all three were in the truck together for a test drive longer than sixty seconds doesn't mean TB was shot at this time. I still think MSs role was to disable him until they reached the farm. If they had killed him at Trinity why wouldn't they have done the plate switch and phone disposal right then?
I think MS has a reason to distance himself from the crime this early in the test drive, because he was complicit in one way or another. It makes no sense to hop out sixty seconds into the test drive. Why come along at all?