Prayer for Travelers on Public Transport

How should a person traveling by bus, train, or airplane conduct themselves regarding the Amidah prayer?

As explained in the Shulchan Aruch (Siman 94, Saif 4), regarding one riding in a carriage or ship, if he can stand, he should stand, and it is not like riding on a donkey where leniency was given that even if he can dismount, he does not need to do so, as derived from the words of the Shulchan Aruch (there) and the Biur Halacha (d"h היה). However, there are those who disagree with this ruling and hold that one can always sit while traveling in a carriage or ship, see below. And in the Taz (there, s"k 4), it is questioned what benefit there is in standing in a carriage and wagon, for after all, he is moving due to the movement of the carriage and ship, and as ruled in Halacha, riding is like walking, and walking and sitting have the same rule. And the Taz answers, here are his words: "Regarding prayer, they did not require praying standing except to have the awe of the Shechinah upon him, and in this, it suffices even standing in a carriage and ship, although it is not called standing due to the movement of the carriage and ship." However, in the Pri Megadim (there and in s"k 5), it is stated that walking is preferable to sitting, yet in Rabbeinu Yonah (Berachot 20b in the Rif's pages), it is explained like the opinion of the Taz. And the source of the ruling that even if he cannot stand fully but needs to lean and support himself on a pole or similar, it is preferable to do so, is as explained in the Mishnah Berurah (there, s"k 24) that prayer standing with support is preferable to prayer sitting, and it seems this is the same rule regarding standing with support during travel, even though he is not fully standing.