I usually plot a route on cycletravel and load it onto my Garmin Touring as a GPX track so the Garmin can't re-route what I've plotted. I turn all the bleeps and navigation off, leaving me with a line on a map and an arrow for my position.
The main thing to remember IMO are these things are tools for you to use, they are not your master! Because you've plotted one route, shouldn't stop you doing something different, you can always find your way back. Whenever I travel in unfamiliar areas I'll always have a paper map. However good the electronics, there's always a possibility of failure and they can't offer the bigger picture that a map can. if I haven't already got a route plotted, I can use the paper map and Garmin to do so, I find the Garmin doesn't do a bad job as long as you don't have too high expectations and keep the waypoints close together.
I've never seen the battery issue as a concern, I have a power pack that can keep all my electronics topped up and go days between charging, as a back up I also have an AA to USB pack, though I've never needed to use it. I recently bought but not yet used a dynamo charger, I'd planned to use on this years 4 week tour including a lot of remote areas, I'm not sure I would have needed it, but there is something reassuring about being self sufficient and I already had the dynamo and lights.