rat rack question

So I'm going to get some ASFs and want to build a rack. Is there any reason why people dont make the sides out of full sheets of plywood? is it just an air flow issue?

Can anyone see a problem with this design? I also would be keeping it in a garage that is on the cool end. I would add some flexwatt to the sides with a thermostat of course to maintain a comfortable temp.

Thanks,
Luke

In my opinion, we leave them open for ventilation and bc they are easier to roll around when they are lighter :) So us clean freaks can sweep or catch loose rats easier.

How is the garage in the summer? I'm not sure how well they would do in the heat without plenty of ventilation.