Low humidity is great for metal, bad for rubber and plastics.
High humidity is great for rubber and plastics and bad for uncoated metals.
I was going to suggest a big plastic bag and tossing in some desiccant inside before sealing it. (Assumes the volatile fluids have been removed from the bike.) But, the plastics and rubbers will out gas faster.
So, you have access to a temperature stable, humidity stable closed environment?