I believe that even 1/8 is going to be way too thick for the widest setting on your platen gap. Also I don't believe foam core, standard or the more expensive acid free (which has a more matte finish) will take standard inkjet ink since there is not a inkjet receptor coating on it. Thus more than likely it will smear.
I have worked with a print shop that ran prints on foam core, their unit could handle 1/8 and 3/6" and the ink used was more like a solvent setup.
Paul