I am replacing some old 8"x8" ceramic floor tile with some new 12"x12" tile. The old tile was glued to a double layer of 3/4" plywood subfloor. When I removed the old tile, some slivers of the plywood came up with the tile. This is in my front entry way, so I don't have the option of installing a layer of cement board on top, as I would not have enough clearance for my front entry door. I also can not remove one layer of the subfloor, as I have a closet and some railings to contend with. What are my options for preparing the existing subfloor for the new tile? Would it be best to set the new tile in thin set, or glue? Thank you.