I'm thinking of getting a gps unit for touring - I usually guess mileage because using the phone apps (Endomondo, Strava, etc) eats the battery. In looking at the Garmin reviews it doesn't seem many of them last much longer than a phone. Charging every day isn't really an option. Anything out there that can last multiple days? I really only care about tracking distance, I can get other data and directions from Google maps. Thanks!