Do you have the AT? If so, how thick is the mat on it? The KAB mat, as advertised, is 1/4" thick so if the AT mat is too then you're okay.
If the AT mat is less than 1/4" thick, how far does the spindle protrude from the platter (without the mat in place) before any bevel or other reduction in its diameter? I'd say anything around 1/2" would be plenty for a 1/4" thick mat.
John