This depends on state law. In Massachusetts where I practice, the nomination of guardians does not avoid court proceedings, it just means that you get to pick who will be appointed. That may or may not also be the case in your state. While your state may not be legally bound by your nomination of a successor guardian after your child is over 18, it’s likely to give it considerable weight.
Harry S. Margolis practices elder law, estate, and special needs planning in Boston and Wellesley, Massachusetts. He is the founder of ElderLawAnswers.com and answers consumer questions about estate planning issues here and at AskHarry.info.