Record the ride twice for redundancy. Use one of the Garmin on the fly recording solutions suggested. Also, use an android phone in airplane mode, e.g., Samsung Galaxy S5, with two extra batteries. Use Wahoo dual band sensors for Garmin and android fitness app connectivity. Go ride for 60 hours.
Unlike iPhones, you can run GPS without data in airplane mode with android. Expect very long battery life and hot swap capability. I've done it many times running Strava.