Homeschooling is legal whether it's relaxed, structured or unschooling. As long as your child is going with the state's laws. The states don't stipulate that you must school is a certain way. They just care that your child is testing within a certain percentile.
Now saying this, if you were to go to court and have to defend yourself in the way you homeschool (which IMO shouldn't be happening since it is legal anyway) I wouldn't advertise that you unschool. Unschoolers fall into a very small percentage and not enough folks understand it yet so it it's better to say you homeschool and draw from many resources rather than using one packaged curriculum. Everybody at this stage is comfortable with the word "homeschooling."
If you want to get around it altogether, that is the testing, registering and state legal stuff you can do an umbrella school. One such school would be West River Academy.
http://www.westriveracademy.com/
This way you are free to school as you like without the state or your Ex. on your back. But remember this one thing. Unschooling is legal.