Applebee's in Fargo out by the airport is usually a good time. . .
No, all seriousness aside, though I love North Dakota and have been all over the state, it's a good question and other than going up into Canada from Grand Forks, or going out west to the Little Missouri River and Riverbend Overlook and Oxbow Overlook areas, I don't have much info for camping and good dirt road possibilities. Check the images at both of the Overlook links, though; there are some interesting vistas and I wouldn't doubt some interesting roads to ride, too.
At Oxbow Overlook there's a sign about Teddy Roosevelt marching some boat thieves he caught "overland" to Dickinson:
I'll be interested to see what info others have to help you, too.
I'd like to get back out to Fargo this summer/fall sometime to see old friends and roam the wide open prairie a bit, and if I do I'll give you a bit of heads up, and if you're into it, we'll go explore somewhere. At the least, get together for a meal or something.
Get's pretty cold up that way. . . I mean in winter when the weather maps show the coldest spots in the country, it always has that little purple dip coming down from Canada that include Grand Forks and Fargo. I was there several winters in a row, working, and it was common to have -25ºF temps for days on end. That's withOUT the wind chill. All the hotels have duplex outlets every 25' or so around the outside of the building so everyone can plug in their block heaters.
We get together, I'll tell you the story about the guys from the west coast who delivered a plane up there, and the scene they caused at the Applebee's with coffee and throwing it into the freezing wind. . .