The plastic/tape body cast is finished for all intents and purposes; the process only took a couple of hours to complete.
On Tuesday we tested a mixture of wood glue and water on an old t-shirt; after a few hours the technique didn't seem to work but by today the fabric was nice and stiff; I'm guessing a thinner fabric like a white sheet will do even better.
There is an issue regarding the weight of the wet treated sheet on the body cast; resolving the issue will require either strengthening the body cast or using lighter fabric; probably both.
At this point I think it's obvious we need to stuff the body cast with something like packing paper which is easy enough to find. To stabilize the cast in the exhibition space, we've thought of either using a wooden armature/skeleton to stand the cast up or suspend the sculpture from the ceiling of the bridge between Langford A and Langford B/C discreetly with fishing wire; since the sculpture will wear old heavy work boots the weight of the boots will "settle" the cast to the ground.
As for an alternative to the bedsheet, I've discovered that cheesecloth and bottled fabric stiffener can make striking ghost-like structures: