Ken,
I would plant these at the same level until they get larger and put on some natural girth in trunk. Other than if you are going to try some root pruning of the tap root.
I have found that unless they are in active growth (putting on new growth) that it is not a good time to prune. They recover very quickly when in active growth.
They can be in a state of dormancy and still have their leaves. Not necessarily leafless.
Rick
