unencumbered has one shortcoming: it almost always requires to be used in the form unencumbered by {something}, which means that to describe a person, you have to list the things by which that person is not encumbered. I think that can be a little clumsy and unclean, and that it might be in better form to just use a word that doesn't require you to list a set of specific things.
You may want to consider carefree, insouciant, untroubled, or perhaps even easy-going, in certain contexts.
If you word your phrase carefully, then light would also be a great word for the task --- I think that to live lightly is a particularly nice and expressive phrase, though that may just be my personal preference. (I think it would work well in this context because the burdens you describe are necessarily heavy, so light works well as the obvious antonym.)