Good luck with however you decide to display/mock display/not display your glass plate negatives. These decisions are rarely black and white (no photographic pun intended). We make the best decision based on the information available and the needs of our collection/organization.
In belated response to your question, I specialize in the preservation of archival materials including photographic media. I travel a bit with my work, including the US, and would be happy to help in any way. I also suggest contacting the American Institute of Conservation for a listing of resources in your area. Feel free to contact me directly at email@example.com.