I don't know anything about the company you are trying to go through or which ones would be better, and unfortunately I've never made a living will either. I am an LPN though (licensed practical nurse), and have worked in a variety of long-term care settings. I've seen people go through these things.
If you are young, you probably want all life saving measures. If you are in good health, your chances of surviving severe injury are higher anyway, and most young people have a strong desire to live as long as possible. As people age, suffer from chronic or painful diseases, or become disabled, sometimes their priorities change in how they view life-saving measures. This is really an individual decision no one else can make for you.
For what it's worth, being tube fed isn't necessarily on the same level of "intervention" as, say, breathing on a ventilator. For instance, there are people with serious digestive problems who live their entire lives on feeding tubes (often called g-tube, PEG tube, j-tube, depending on the type), and are still able to maintain quality of life. The part of the tube that is in the person's abdominal area can be hidden under clothes, a person can go out in public in most circumstances without it being obvious to others that they have a feeding tube. Depending on what kind of tube they have, they may not be able to go swimming or wear tight clothing, but those are often the only restrictions.
I know you are talking about a temporary life-saving measure, not a permanent situation. I'm just trying to put things into perspective though. Even if you are determined to be in a vegetative state or brain dead, being removed from a feeding tube is not necessarily the same as "starving" to death. People can be kept comfortably sedated as their body is shutting down, it's not like you will be left alone just because this decision has been made. When people die natural deaths of old age or disease, there comes a point toward the end where they simply stop eating, and it can be days from that time until they actually pass away. This isn't necessarily painful, it's just part of dying. Even if a person if dying of an injury and a decision is made on their behalf to let them go, this process can be simulated.