A fast is valid without the Saher (pre-dawn meal), though there is Barkat (blessing) in taking the Saher, and its Mustahab (recommended).
So you can skip Saher, or take it hours before its time and the fast will remain valid. If you want to take it at its proper time, you can take a snack with you while you commmute and eat it at the right time by checking your watch etc.
In Saheeh Bukhari there is a chapter titled
باب بركة السحور من غير إيجاب لأن النبي صلى الله عليه وسلم وأصحابه
واصلوا ولم يذكر السحور
Sahur is a blessing but it is not compulsory, because the Prophet and
his Companions observed Wisal and did not mention Suhoor.
This chapter lists the following Hadith:
Saheeh Bukhari The Prophet (ﷺ) fasted for days continuously; the
people also did the same but it was difficult for them. So, the
Prophet (ﷺ) forbade them (to fast continuously for more than one day).
They slid, "But you fast without break (no food was taken in the
evening or in the morning)." The Prophet (ﷺ) replied, "I am not like
you, for I am provided with food and drink (by Allah).
Saheeh Bukhari The Prophet (ﷺ) said, "Take Suhur as there is a
blessing in it."
And Ibn Hajar, in Fath Al Bari, links it to the following Hadith:
Saheeh Bukhari Allah's Messenger (ﷺ) forbade Al-Wisal in fasting.
So, one of the Muslims said to him, "But you practice Al- Wisal. O
Allah's Messenger (ﷺ)!" The Prophet (ﷺ) replied, "Who amongst you is
similar to me? I am given food and drink during my sleep by my Lord."
So, when the people refused to stop Al-Wisal (fasting continuously),
the Prophet (ﷺ) fasted day and night continuously along with them for
a day and then another day and then they saw the crescent moon (of the
month of Shawwal). The Prophet (ﷺ) said to them (angrily), "If It (the
crescent) had not appeared, I would have made you fast for a longer
period." That was as a punishment for them when they refused to stop
The argument is that the Prophet and the Sahabah observed Wisal (continous fasting for days without a meal at nights), and whereas this was discouraged the fast was considered valid ... since Wisal is valid, not eating Sahoor is valid since Sahoor would interrupt the Wisal.
From Islamic Jurisprudence According To The Four Sunni School:
Desirable practices associated with fasting:
(3) Taking a pre-dawn meal, however light, even if it consists of
nothing but a sip of water. This ruling is based on the words of the
Prophet:"Partake of a pre-dawn meal, for it holds a blessing." The
time period during which the pre-dawn meal is to be taken commences
with the beginning of the latter half of the night. The latter one
partakes of the pre-dawn meal, the better, such that there is no doubt
concerning the break of dawn.
The book does not seem to mention any disagreement among the four major schools on this issue.