So I've been doing some reading on people using tablets, specifically the iPad, as a navigation tool. Everyone seems to be on the same page that you'll need an iPad with the GPS installed but I'm struggling to find more details on actually using the unit. There are obviously several navigation and exploration maps for the iPad in the app store but will the iPad with built in GPS really be a reliable unit to be used on U.S. based off-road trails where you're not in range of cell signal? I have seen a few people with GPS boosters that plug into the tablet but would a setup like this be used with accuracy off-road? Any information would be helpful, thanks.