couple of odd thoughts . . .
16 x 30 . . . inches, one presumes? 40 x 76 cm?
#1 - not gonna go in a home dishwasher
#2 - any plastic 3/8 thick will (eventually) warp
might want to look at flexible pastry mats. 16x30 is a size issue; big ones will be a $ issue.
dunno' about the granite issue. I roll out pizza dough, puff pastry, pie dough, biscuits, etc right regular on granite.
in fact, my (prior house) marble board has inches of dust on it, down in the basement.....