...I'll admit I am not an expert on these things, hardly, but...if this Denny's is what one might call a liminal place, and we ourselves are dead, thus...liminal beings of a sort, I wonder that it may be possible. Especially given that the Wizard seems to be focused on preventing us from contacting the school's living. However, 'Plan B' showed that he is not wholly capable of preventing all contact that comes from us, so long as we're not contacting the school directly.

It's worth trying, at least, so long as SQUIP is not put in any danger.