@tablejockey, I have a 1200G and am able to use a SOTA reflex clamp with the stock mat. I’m not certain but I suspect the 1300G has a similar dimension. The 1200G spindle is shorter than normal.
So far mine is stock, although I got one of the recommended Teac paper mats to try. That is thinner so will provide more spindle area to grip, not that I seem to need it.
BTW, I was disappointed when Technics decided to retain their older cosmetics in their new, redesigned line up. But that didn't keep me from buying one.