I did cover the motion of the earth as it spins and makes its journey around the sun as well as the sun and earth making their journey around the MilkyWay in an earlier post. So much for one of your assertions.
Yes, you're quite right - you did. But not with me, and it is an important bit of what we are talking about. And we shall see, it has already bore fruit.
How would you propose to speed up the earths rotation to c as well as it journey around the sun to c and their journey around the universe to c.
I don't really care. Such physical difficulties are immaterial to our discussion. And if we leave the relatve speeds as they are, they will still have an impact upon what you are claiming, albeit with much smaller effect.
So, the question remains. Is the 2 feet measured relative to your "fixed" salt flats, or are you also taking into account the motion of the salt flats as they orbit the Galaxy, but just failing to mention it for some reason?