Very little wood is actually the advertised dimensions. Much as a 2x4 is not actually 2" x 4". 1/2" ply is meant to get a layer of laminate on it, then it will actually be 1/2"... Just use normal 1/2" T-molding. You'll have about 1/32" of an inch overhang on each side, barely enough to notice. If it bothers you that bad, they make little tools to shave the molding down on each side to match the material.