@James Gielow Thanks James for inviting me!
In true conservator fashion, I think I have more questions than answers about this specific scenario, but here's a couple of my thoughts.....While a desiccant sheet may offer some benefit in a small space like a frame that is completely sealed, I typically recommend silica gel when working with exhibition cases since it's a larger space. A sheet or two of paper in a case won't provide much benefit. Assuming your case is air tight, silica gel would work for a period of time before it gets exhausted and walks off the job. It would need to be replaced but timing varies depending on the conditions. Do you plan to monitor the humidity in the case during the exhibition?