OK, here's what I decided and it worked. Put some ashes in a travel-size Gold Bond Medicated Powder bottle (opaque) in my checked bag. Got into Panama last night with no issues at all. Knowing the recent Roman Catholic pronouncements against taking possession of a loved one's cremains and scattering them willy-nilly, and seeing that they won't even sell alcohol here today in observance of Good Friday, I'm not going to bring this up in conversation with anyone.

Transiting the Canal tomorrow night.