A winch sounds good, but not very pratical. I do have a track winch. It has two metal hooks on a long stap that mount to the windows in your track, then you hook the long strap or rope to a tree or something out in front of you. As you throtle the sled the strap/rope starts to wind around the track pulling you forward, or backwards. The bad thing is you have to roll the sled over and unwind the strap from your sled, the good thing is if you are by yourself, you have a way to get out. Not very practical in getting out of a normal stuck, but great if you have no other way. With this winch you don't need a battery, or a heavy electric winch.
Hopefully your brother in law is a nice guy and will help you get unstuck.
Hopefully your brother in law is a nice guy and will help you get unstuck.