Ok, @Oliver_Smith once the fatbike parts come in here’s the plan: 
Find yourself a nice, flat, open field, preferably without footprints etc. A school football field could be ideal.
- Get on your fatbike and ride a loop, maybe a figure 8, or even something around some trees if there are any nearby. The first lap is going to be quite difficult, at least for power. It’ll take a lot of watts if you’re pushing through say, 3-5" of snow. (any deeper and it’ll be impossible, so this is very dependent on snow depth)
- Then just keep following your track, the next few laps you’ll be trying to stay in the rut you made on prior laps. This will be a great handling exercise, trying to stay in the rut. As soon as the bike goes off, you have to try and recover, but it needs to be a very smooth gentle turn back in. (It’s basically like riding sand)
- Then after say 3 or 4 laps, you’ll have a lovely little path you’ve created, then you can work on maybe going a little faster, and you can play with the handling even more.
- One thing I’ve really begun to notice or appreciate, is how your power input to the back tire can affect your handling and turning. This winter has been so good for fatbiking, I’ve really been getting good feedback. I’ve noticed how when I’m turning, I can get to that pint where you turn the front wheel, start the turn, then you apply force through the pedals, and the rear tire can “push” you out of the turn, it’s brilliant!
The good news, especially that your wife will appreciate, is with a flat snowy field, there’s not much to hit if/when you tip over.
I did something similar a few weeks ago. A little park near the highway and Weber (Montgomery Park). The snow was right at about the maximum depth where you can still reasonably ride through it. (When the underside of your pedals just kisses the top of the snow beside your rut, that’s the max.) The first lap was really hard, then the subsequent laps were a skill challenge of staying in the rut. But it got better and better. But the feedback on your handling and getting a sense of your limits is just great. And yep, I wiped out a couple times, but again, just falling on flat ground into snow, so no big deal at all.
