Well, yeah, that is impressive....
The only other guy I know with more than three GT/CS cars is Ernie Gonzalez in So. Calif--with four or five at any one time, and one HCS, too.
About Trunk mats...
When i got my car in '74 (for $995), it had a plaid mat, kinda ratty. I still have it. "Most" people that answered my GT/CS survey from about '85 to '90 said that they had plaid mats, too.
It's all in the supplier at the time. If the OEM supplier ran out of plaid, they sent speckle. I'm sure someone knows what type of mat was primarily used for each of the three assembly plants. In a general sense, plaid was popular out here on the west coast--but I wouldn't knock anyone in a car show for having speckle.
Also--some people think that a plaid mat upside down is "speckle".
Maybe this will help.
Paul N.