I experienced an iPad mini heat shut down a couple of times. I use a RAM mount to hold it in the right side corner of the wind shield of the C182. I made a heat shield of .025 aluminum about a ¼" larger all around than the iPad and mounted it between the iPad snap-in mount and the RAM mount ball. I haven't had a heat related shut down since then, but we haven't had any 100F + days yet the summer either.
Yes, the iPad is the back-up to the 720, also usefull for the co-pilot to look up frequencies, etc. while I keep on the magenta line.