A field exchange container, when deployed, acts like an in-terminal trade window.

Costs more than twice what a regular field container costs, so that trust and risking theft with a standard field container still has a place in the game. Possibly requires EP in a diplomacy / relations / finance extension to use (level 4 accounting? or a new extension, that gradually raises the limit on the number of distinct items that can be traded or the number of sequential trades executable with one field exchange container).

This would promote friendly exchanges between relative strangers in the field, while still encouraging people to group up into mutually-trusting corps for greater efficiency.