* Continous tracking on smart phone is easy but it takes too much battery power (we all know this). There are many apps that do tracking (it doesn't appear too hard to do).
* You could use an external battery pack to deal with this. There are lots of these and they aren't that expensive. If you had access to power nightly, you could run the phone continuously with a battery pack large enough. It takes some time to charge the phone this way (and you'd want to take care the system doesn't get wet).
* Dedicated GPS units will do tracking but they can have battery issues too (still better than phones). The Garmin bicycle/running units might be good choices here. Turning the screen off helps alot here. There might not be an easy way of dealing with the data while you are touring.
* Apple doesn't allow for periodic tracking (it appears). Jail breaking might provide access to apps that will do that for you.
* Using a manual process for taking your location (like using pictures) seems too inconvenient. If A-GPS is availiable, it would help here (or for any automated peroidic tracking), as Burton was hinting at. That benefit won't be available if you are out of cell-phone range but that isn't really going to be that much worse than turning a GPS unit on/off to conserve battery.
* Another approach is to get an external Bluetooth GPS receiver. These appear to have good battery life (around 12h) and cost about $100. The GPS antennas these use should be better than what is used in phones. It appears you'd have to jail break the iPhone to use these. It's possible that these have memory so that you wouldn't need to keep the phone on all the time to get the data. Ideally, the unit would support BT 4.0 LE (which uses less power).
* Android might be a better choice for this than iOS.
* If you were really hot on doing this and didn't mind spending money, you could get a generator hub ($220 for a wheel with the Shimano generator hub and about $400 for the Schmidt Son hub). And $100-150 for a USB charger (B&L has a light that has a USB charging plug). You could use the hub to charge a external battery pack.
* You want to keep an eye on making sure whatever you do is weather proof.
Last edited by njkayaker; 04-22-13 at 09:49 AM.