i'm TERRIBLE at spatial recognition!
the reason i moved Yellow up was when he outgrew his old hides as well as the 20gal he starting hiding under the substrate and carpet i had in there (to the point where i thought he escaped and was missing...nope, just under the friggin' carpet). he didn't like trying to squeeze into the hides' entrance (exo-terras) so i got him nice, big RBI hides.
i do have spare mediums so i'll put one in there when i get home and watch him for the week to see what he thinks.