Can a person with Celiac Disease/On Nasogastric Tube feeds make a לישב בסוכה

The Gemarah writes (Succah 45b-46a) that, unlike other mitzvot, one has to bless "Leishev BaSukkah" every time they enter into a Sukkah on the holiday of Sukkos. When it comes to Birchas Hatorah, one makes a bracha once in the morning, covering the entire day of his limmud HaTorah. Why is the blessing of sitting in a Sukkah different?

 A rather famous answer is that the Torah is different. One never stops thinking about Torah in general because, at every moment, one is required to learn ( "V'higisa bo Yomam Va'Laylah" ) while there is a set time that one is obligated in Sukkah. Therefore, every time he finishes his meal, there is a break until he decides to sit down and eat the next time in the Sukkah, thus warranting a new blessing.

While this is a contentious issue in the Rishonim, Rabbeinu Tam writes that since the main act done in the Sukkah is eating, one makes a blessing on the eating, which then covers all other actions performed in the Sukkah, even sleeping, which is more stringent than eating because one can have a temporary meal outside of Sukkah. At the same time, one can not take a nap outside of Sukkah; nevertheless, since eating is the main act performed in the Sukkah, one makes a blessing on that to cover all others actions."

The Shulchan Aruch & Rama (639:8) state that the custom is to follow Rabbeinu Tam, the second opinion in the Tur, that we only make a bracha at the time of eating. 

The Mishna Berurah (46) explains that since there are various opinions, one should preferably eat something from the 5 grains and make the bracha of Leisheiv, which will then cover him for any future dealings/meals, he does in the Sukkah afterward.

This suggestion by the Mishna Berurah can be hard to accomplish for somebody with Celiac Disease who can not eat the 5 grains. Should they not make a bracha? What about somebody on nasogastric feeds?

The Achronim and poskim suggest a few solutions for those unable to eat the 5 grains:

The Kaf Hachaim suggests that the best thing to do is hear the bracha from somebody else eating the 5 grains.

Rav Shlomo Zalman (Halichos Shlomo Sukkos 9) and Rav Elyashiv (Ashrei Ish 3:26:18) are both of the opinion that since a person with Celiac Disease can not eat the 5 grains all year round, eating what they usually eat is considered their main¸eating which would then warrant a bracha even though it's not from the 5 grains.[1]

[1] Adapted and translated from Rabbi Yossi Sprung on medicalhalacha.org