An idea for training is to look at a topographical map of an area new to you and find some old roads (labeled 4WD on topo maps) and pick a route that you might like to find.  Disclaimer: When you get there, you may find the road or trail is now a paved development road, private property, or completely grown over!  That's part of the fun, you just don't know.  We do a lot of scouting for our races and that's what we do, we find routes.   When you do make it onto a trail that's navigable, use your map reading skills to keep track of streams, other trails, town boundary markers, etc, along your way and you'll be doing your own mini adventure race (with "checkpoints")!  It's safest to tackle these trips with a buddy!  Recently we tried to ride around Dan Hole Pond in the Ossipee Mountains but found one "road" grown over; it took so long to slog our bikes through the woods that we ran out of daylight.  Kind of like a mini adventure race...light was our time cut-off and we didn't finish...a DNF for us!  But we had fun and saw a moose!
< < < (sample here, not meant for you to ride, just to get an idea of what one might look like)