I have been thinking about building a cooling
room that would hold a couple of tray trucks.

A cooling room for chocolates is IMO and expensive use of limited
space. in the long term.

The room for chocolate work should be cool anyway....but
Its better to have cooling tunnel inside it and then install other
equipments needed for the chocolate work.in that particular room.
There is no need to run between two rooms as there is wasted effort and
working efficiency running between rooms from the point of time and
motion study..