With 4 seasons of fatbiking under my belt, I've found that anything over 7'' of powder is nearly impossible to break trail in. For Nemo, several rounds of snowshoeing by a group of people would be necessary to get a good base. Now with the rain and warmer day temps this week it mite not take as many passes to pack it down. However if one person hikes through without snowshoes on an already semi-packed snowshoe trail in warmer conditions will ruin it pretty fast, especially if it freezes after. I have also found that if a trail get snowshoed then ridden in good with the FAT tires, makes for some amazing groomed singletrack-if it stays cold.
That being said all snow is different every time it seems like and there are a lot of factors that make it easier or harder to ride in. There is a learning curve just like everything else.