II would at least  insist upon monitoring (e.g., glue boards, sticky tape) the exhibit area* to determine if the food is attracting unwanted guests and of what genre, with an understanding that exhibit would be moved/dismantled if harmful pests are caught.  It would also be advisable to determine (1)  if the unwanted guests are roaming about (monitor adjacent areas, especially near significant and/or vulnerable artifacts) and (2) how long these unwanted guest stay around (kept some monitors around several days/weeks after this exhibit closes).

 

My underlying thought:  "The powers-to-be"  may be resistant to "documentation" you present from an "archives" -- as in go into denial mode (i.e.,  that was someone else's problems/mistakes and it won't happen here)  and then chose NOT to stand up to immediate/ local pressures to have the exhibit.  So if you can develop evidence on their home turf, they will at least have first-hand experience/evidence and hopeful be more willing to deal with the conservation issues.