We use a 16' stock trailer that has been modified with removable doors to haul 5 bucks, separated in stalls or up to 12 does with all doors removed. We had the openings along the side covered with steel plates that have 2" holes in them every foot or so and have butterfly vents on the front and roof vents for ventilation. We do not have A/C and haul a lot of deer to LA but we time it so it is dark when we get further south. We were told by one preserve owner that he didn't want his deer hauled in A/C do to the big difference in temps once they arrived in LA