This sound is very rare, I only know poŭpo and toŭfuo. Because of that, it is probably hard to pronounce for some speakers. Yet, oŭ can be useful if we need to create a new word that sounds very similar to the original one. Should we use oŭ or should we use alternatives?
No, you should avoid using "oŭ" when creating a new word. Traditionally, Ŭ only appears after A and E, and this convention is still generally applied when creating new words. The only word with "oŭ" that ever managed to become a popular word was "poŭpo", but even that one is nowadays usually replaced by "pobo". The word "toŭfuo" was never very common: As soon as tofu became popular outside its regions of origin, the usual Esperanto words for it have been "sojkazeo" and "tofuo".
If you introduce a word with Ŭ in a non-standard position, it is likely that it will not be accepted by the Esperanto community, as most people follow the traditional convention, because deviating from it makes Esperanto more difficult to pronounce for many people.
When creating an Esperanto word, one often has to deviate from the original pronunciation anyway. The additional deviation from original pronunciation caused by avoiding "oŭ" is really not a big problem, certainly much less of a problem than introducing "oŭ" as a new sound combination that everyone needs to learn to pronounce.