Yeah, what JimG said
Scott, your wording is fairly vague IMHO.
While Catholic guidelines talk about the presumption of care, even they admit that not all treatments are appropriate for all conditions and that it must be determined individually. Your Bishop may be a swell guy but it is not really his call. He’s just there to advise.
Check with the law in your area to see which family member would have the right to make choices for you (IIRC it is spouses, then adult children, siblings, parents, then other kin)
Then talk with that family member about your wishes…and have witnesses especially if members of your family disagree with each other or you.
I think you’re allowed to assign responsibility to another, out of sequence, if you wish.