No problems whatsoever in about 3 years of Skydemoning! iPad Mini 2, wifi only so external Bluetooth GPS (one of the GNS ones, can't remember exact model number), and an A5-sized kneeboard that has the iPad inside, and a standard clipboard on the outside (for paper plog, notes etc). That way, it stops the "magenta line hugging" issues, as I have to actively open the kneeboard to look at Skydemon.
I've never once had an overheating issue, and with external GPS the iPad battery lasts for about 5 - 6 hours on Bluetooth. Only had one or two GPS drop-outs mid-flight in those three years, with the GPS unit buried in my bag in the back of the plane.