Same thing I was thinking. Make it a func_illusionary like skdr said, then copy the brush and put a null texture on it, that would stop the clips from falling threw.
Seems to work. More testing is required.
Actually the NULL doesnt show up as a Hall of Mirros effect thankfully through the func_illushionary. However, the player model still goes solid black.
Here is Freeman doing his thing standing on a func_illusionary, CLIP, and NULL all in one.