Given the scale of this creature I don't think that it would be practical to render it in physical form. But perhaps this one would be best suited for 3D projection mapping.
Do up a 3D animated model and make it feel like its inhabiting a space much larger than the actual proportions of the room. then later in the path should it collapse or be defeated could render a portion of the creature in physical form to give patrons a sense of its size.
I especially want to use 3D projection mapping to make the space feel much larger than it actually is. Then couple that with some 3D soundscapes and perhaps even smells.
I tend to not see or rather not hear of haunts utilizing scents to bring their creations to a new level. I'm not sure if there are effective ways to produce some of the creepier scents out there without needing to actually have stuff like rotted meat or blood about. Also would like to avoid having to clean up vomit. xD