Most counties in the lower 48 have more miles of road then our entire state. But then, for sledders at least, our limited road system translates into jumping off points to access millions of acres of true backcountry.
I ride some hills along a 135 mile dirt "highway" that doesn't get plowed in winter. 65 sled miles to my friend's year-round lodge. There's another spot I like on the south side of Denali Nat'l Park, a big, high bowl that's 35ish miles from the parking lot. The run in starts on groomed trails, drops into a river run that can be 20 miles of powder, then a long climb up a hogback that is a playground all in itself. All that before we get to "the spot" where the "real" riding begins. 10 gallons spare gas is pretty common--enough to get there, ride and make it back to the truck/cabin.
It's a major drive to get to AK just to ride, so plan on a whole month!! Mid March to mid April is the sweetness.