I'm a sport pilot and Avgeek. In a couple of weeks I'm flying on a commercial flight to Guatemala. Would it be safe/legal to take my dual electronics Bluetooth GPS so I can follow along on Foreflight? Also if my Nav/Com was in my backpack could I listen to ATC via headphones? I'm wondering about TSA issues, safety issues, etc. As a pilot I always find it difficult to just sit in the back. I'm looking for airline pilot feedback, not random opinions.