I do have a suggestion, but I hope you read this the way I intend, and not as a smartass comment, so here goes: have a positive attitude about this. I mean, if this is a necessary procedure, and you agree to have it done, concentrate on the fact that the medical know-how exists to do this without killing you outright, and perhaps even get you to a "healthier" state than you are now.
Negative states of mind add even more stress to the whole thing, you know?
Otherwise, do have hubby bring you a Primal lunch bucket each day you are in the hospital, as soon as you are allowed to eat, and it sounds like you have thought of everything, otherwise. My only other suggestion is to add a homeopathic general tonic like "Bioplasma" if you are open to/familiar with homeopathics (not all are - I'm totally aware many consider it wooooooo).
I have a mantra that I have spouted for years... "If I eat right, I feel right. If I feel right, I exercise right. If I exercise right, I think right. If I think right, I eat right..." Phil-SC