My Rabbi wrote an article on this here.
Question: I am going on a family outing on Chol Hamoed. Do I need to ensure that I eat in a Sukka?
Answer: The Gemara in Sukka (26a) teaches us that one is exempt from eating and sleeping in a Sukka while travelling because teishvu kaein taduru, one doesn’t alter one’s normal living habits in order to live in a Sukka. Rashi explains that just as during the rest of the year living at home does not prevent one for travelling on a business trip, so too one may make a business trip (over Chol Hamoed).
The Shulchan Aruch (OC 640:8) paskens like the Gemara, though the Rema adds that debt collectors travelling to villages which don’t have a Sukka will be blessed if they are particular to return home each night. The Mishna Berura (260: 40-45 and Biur Halacha) explains that one should look for a Sukka. If there isn’t one around one doesn’t need to go to the bother of building one just for a night, though should for a longer stay.
R’ Moshe Feinstein (Igros Moshe OC 3:93) qualifies the Gemara’s exemption like Rashi: While may one travel for business purposes of for a mitzvah, one going on a trip for pleasure is still required to eat (and sleep) in a Sukka. One doesn’t need to travel for pleasure, and one should go out of one’s way, and forgo a little extra pleasure in order to fulfil a mitzvah. Elsewhere (EH 4:32:8), R’ Moshe writes that tourists who visit another country and particularly want to see the sites may travel without a Sukka if they can’t delay visiting until after Yom Tov. R’ Ovadia Yosef (Yechave Daas 3:47) also holds that one can not eat outside of a Sukka when on an outing.
R’ Elyashiv (Hearos Lemasesches Sukkah p114) challenges R’ Moshe’s arguments. As it is common to travel for pleasure, it should be no different to traveling for business, and such travel should be included in teishvu kaein taduru. Rashi, he writes, used business as an example, and other Rishonim don’t stress any type of travelling. Additionally, one who has a Sukka and leaves it for a short trip is not considered avoiding the Mitzva.
While one has what to rely on under emergency, ideally, one should be particular to prepare food that doesn’t necessitate a Sukka when travelling (See Shulchan Aruch OC 639:2).