As I've posted elsewhere, I'm about to take my annual long hiking trip up to Canada. I will be at several different wilderness hiking lodges for a week to ten days at a time. The car gets parked at a meeting area or staging area and I go up to the lodge and come back to it when I leave the lodge. There's no cell phone service at the lodges and I need to pack as light as I can for each lodge. I have no need for my phone at the lodges and I normally would turn it off and leave it in the car. But with all the issues of unlocking the Model 3 I'm wondering if it's a good idea to leave my phone and have only the key card. I've never had the car fail to unlock from the key card, but I'm wondering if that's ever happened to anyone? There's only the one outside sensor for the key card and if that were to fail I'd be locked out. At one of the staging areas where the car will be parked, there's no cell service, so Tesla could not remotely unlock the car, even if I made my way to town and phoned from a pay phone. Is it safe to leave the phone and just rely on the key card? Or should I keep both with me to be on the safe side?