What is preferable in my situation: completing my Ph.D. studies and teaching in higher education, given the presence of intermingling (ikhtilāt), the prohibition of shaving the beard, the possibility of not shortening the garment, and performing prayers on time; or working as an engineer in companies with similar conditions but less temptation from immodest display (tabarruj) and less free time for seeking knowledge?

If you fear temptation (fitna) in your field of work, then it is obligatory to avoid it, even if you are compelled to work abroad. If the working conditions in teaching and companies are similar, then the choice is between the temptation of ostentatious display (tabarruj) and the benefit of increasing one's knowledge. Since the temptation of women is great, if you fear being tempted by immodestly dressed women in teaching, then you must avoid this field, even if it means sacrificing further knowledge; because warding off harm takes precedence over acquiring benefits. However, if you are secure from that temptation, then there is no blame upon you for working in teaching, especially with the benefit of increasing your knowledge.