I can't swear to your area or how primitive the roads are, but all the roads around here are in the Garmin maps. Including the many unpaved roads.
Even if the roads aren't in your maps, you should still be able to navigate a .gpx.
Seriously, what were you looking at? Because I'd like to know if I'm missing something on mine, too.
You can't update Edge maps online anyway (except maybe the basemap gets updated periodically with the firmware, I suppose). You have to buy a new disc or chip.