Here's my two cents:
You said you want to mentor kids (as you motivation to getting your PhD). Have you thought of skipping the PhD & getting into teaching high school (and coaching too)? It's not that hard to get into teaching. You can get a provisional teaching license (that will give you 3 years to take all your education classes) & jump right into the classroom. Or, you can go back & get your teaching degree, then start teaching (but this will give you some teaching experience).
BUT, and this is really important, there is often a SHOCK & AWE to career changers who step into high school. What you think public education is & the reality is can be very, very different. As a general rule, you have to remember that kids are kids. They come with baggage & immaturity. Homework is really a thing of the past now (unless you teach honor or AP classes). They don't really care about class content because they're teenagers. Kids don't care about how much you know, they want to know how much you care. But, they'll do your work.
If you're interested in mentoring, then this is probably your best option. And, the cheapest. And, the fastest. High school kids need more attention than ever. Getting into coaching is a double-win for mentoring & your love of running too.
I never thought of getting into public education, but years & years ago, I couldn't find a job teaching college & ended-up in a high school (really over qualified). I got my provisional license. I teach all upper-level classes (so I avoid a lot of trouble-makers, except when I have hall duty or cafeteria duty). I coach XC & track too. But, I have tenure (job security). I have a good retirement. I have health insurance.
I never thought I would do this. But, it's not a bad existence. And, retirement is a pinpoint of light about a decade away.