Sound linkage using "l" before a vowel: l'on
Excerpt from Le Petit Prince:
"Or un baobab, si l'on s'y prend trop tard, on ne peut jamais plus s'en débarraser."
I understand that the "l" in "l'on" is not a definite article or COD. It does not refer to anything, but is just there for a sound linkage, to make the sentence go more smoothly when being said.
My questions:
Is the "l" added only to the subject pronoun "on" as a sound linkage? Or can it be added to other words that begin with a vowel or "h" too, like "autre" or "hôtel" as a sound linkage?
If it can be added to other words (that begin with a vowel or "h") besides "on", when do you add "l" as a sound linkage? Is it when the word before ends with a vowel?
If I remove the "l" and make the sentence into "... si on s'y prend...", is it still correct?
Merci d'avance :-*