According a monk friend of mine there are three ways to practice. 1) Alternate between worldly employment and spiritual practice. This would mean working part time or studying in the evenings, combining the two as you go along. 2) Taking time out to practice. This would mean worldly employment full time, then stopping this for a month retreat, or taking some time off to study, then afterwards returning to your job. 3) Making practice all of your life, by for example running a Dharma centre, or becoming a monk.
Tom thinks that there are still viable elite pathways, but Huseng and I both think that all the conventional Western academic pathways are increasingly dead ends. So from my perspective, your doctorate would have to be as a private scholar, which is expensive and difficult. It can be done, slowly, on a part time basis or by correspondence in your free time, here in the West. Which if you have a family to support might be your best option. (Huseng's peripatetic scholarly life is only for single people). You could also save up lots of money and travel abroad for a while to study, for example at Rangjung Yeshe, then afterwards return home. In either case the rewards (which will be massive btw) should only be pursued as personal rewards to benefit your own understanding, and not as stepping stones to an academic career. Having said that, if you do return home with such skills you will be very popular in Western Dharma centres, and you will be able to help a lot of people. It is not an unrealistic aspiration, it is a noble one.