Virtually no heat under the boards, most of the heat comes off the driver. It’s possible to mount the driver outside your tent for summer use. .
That was what I was looking at doing if I go that route. As it stands now all my controls are outside the tent with only power going in for fans and lights. With my HID stuff I remote mount the ballasts away from what I lighting up. Even the timer is outside. It's easier to check and adjust things. Having all the drivers mounted to a board outside the tent where they can be messed with would also be a huge plus. It's also less weight on the hangars.
The investment is substantial but they should last.