Mike, all the thinset mortars carrying an ANSI rating have been well tested and many manufacturers like to emphasize the very high sheer bond ratings they've achieved.
But when bonding to many backing materials, such as waterproof membranes, the bond to the membrane is usually required to be no more than 50psi. That's still enough to park a small car on an 8x8 tile, and I just don't know a lotta people who try to park larger vehicles in places like that.
And doing any sort of bonding test with a tile as large as you suggest is neither practical nor necessary. Bond strength is bond strength and making the surface area is not gonna increase or decrease the bond per surface area covered.
The Europeans do have a pull bond test that's not used over here. I'm not familiar with just how it's done. Some folks in our Standards community want to see it used here, but I don't know where that stands.
For mine own part, 50psi of sheer bond is waaaaay more than anything I tile needs to withstand.
Your test design would also not yield much on accounta the Kerdi Board surface is gonna fail before even the cheapest thinset mortar in that sorta test, I'm willing to wager.
And at last, 
