For now just keep your body weight fairly neutral, it's not going to make a huge difference riding a GS in ruts at slow speed, concentrate on being relaxed, pick a point ahead which keeps moving further ahead and is never less than say 10 meters or so. Doing this you have already picked your way around the obstacles.
At each point, tell yourself.... Blue, you're going there, ....Blue you're going there etc etc.
Remember, as with all riding, the bike never go's anywhere your heads not been 5, 10, 15 seconds beforehand.
On a GS with road tyres you'll have very little room for error if it's at all slippy in ruts, get at least a decent front tyre on.