The weather is humid. Can you cover the SLR with two plastic bags and put it in the closet to prevent moisture? Will the desiccant in the bag be too dry to damage the camera and lens?

You underestimate the steam, you can enter through a small crack. Unless you can completely isolate the air.

And if the humidity of the environment is already very wet when you pack, the humidity in the plastic bag will not be so low, and it will be moldy as usual.

The best humidity for preserving photographic equipment is 30%~50%, and most plastic bags are airtight. It is suggested to get a moistureproof box or a damp-proof cabinet.

If you have already bought such an expensive SLR, don't save the money.