True about the nutritinialitive qualities of dark chocolate - but I can tell you from icky experience the tropical dark melts just fine in a kids pocket.
We did this as kinda a veterans day thing - was considering making some spam sammiches too
Try making "genuine" USMC issue style bologna sandwiches
Start by leaving White Bread, cheap bologna and imitation cheese sitting out over night, (week end is better )
Stack as with regular sandwich, DO NOT ADD CONDIMENTS, it spoils the whole effect
Another "Veterans favorite"
Kill a pig, take all useful portions to the butcher for cutting and wrapping,
From what is left take random pieces, 1/4 filling unlined metal container, mix with partially cooked Lima beans, Store for years or till all flavor has been leached from metal,
place over propane torch until bottom is burnt, middle is warm and top is totally unheated add Tabasco (LOTS of Tabasco )
Bon apatit