Exterior unit temp

Got my APO yesterday and am excited to get going. Just did the Heating element prep and boy did the sides get hot when the top and bottom elements were on, which I assume is normal. My question is, does the water tank have to be on if you are not using it? Just seems it would crack with that much heat next to it. Thanks in advance for understanding if this is a stupid question!

We recommend the tank stay attached when cooking.

With the tank full of water?