It is a great idea to spell this out and good advice.

I don’t like at all this idea of “being a burden” on the family as a criterion for withdrawal of life supporting care. I’m an ICU doctor and almost always the family wants the patient kept alive more than the patient does, as the family loves them and doesn’t want to let them go. But the patient is the one who has to suffer the reality of their quality of life. And many will be in nursing facilities so not a “burden” on the decision maker. In addition it is unlikely the decision-maker would use being a burden as their explicit reasoning.

Focus instead on what an acceptable quality of life means to you. Knowing that they are following your wishes is usually what gives people the strength and love to let go.