Here is an upated townhall map with a "trading table". Effectively it's a table that two players can sit on each end and place items for trade on the table without fear that anyone will steal them. I thought of a simple npc extention that could be added later to perform instantanious swaps for untrusted trading (maybe I'll write that once I setup my own server).
I placed it in the townhall because it was the only semos building that had enough spare room and is also a public area. Maybe a basement level could be added to the townhall or inn (where the dungon doesn't overlap).
I also tried putting a wood fence around the table, to make the collision area look more obvious.. but it didn't look very good with the green shadow (meant for grass I guess).