Thank you eastcoast101 for stating what most people seem to ignore. Only about 10% of hs track athletes continue in college. This is not because they have lost interest, they are just too slow to be competitive. The only athletes still competing in college are the ones who were winning everything in hs.
And OP while it is not too late to be recruited for track, (many athletes will still be recruited in their senior year), you do not fall into that category. You do not have any proven track results and do not have the correct plan to get them. You should be signing up for open USATF indoor meets, not trying to qualify for Boston.
The fact that you are training for a marathon will be a negative not a positive. Coaches usually prohibited their athletes from running road races, you simply do not have time to recover if you run long road races during the season. Also mentioning Boston specifically will hurt you, Boston 2019 is already sold out and if a coach thinks you are training to run a qualifier for 2020, they know you will not be giving the team your full effort.
Your best plan is to apply to the schools you are interested in and see if you can find out about open tryouts or a running club, once you are admitted on your own. Based on what you have shared you do not seem to be strong enough athletically to have a coach help you get admitted.
@jvtitmus: What are your 5K & 10K times ?
I contacted the coaches from the schools I applied to and they said that there were no recruitment spots but my times were good enough for a walk on. Already applied to those schools as of a week ago, and yes I do have a quite a few safeties and likely schools, thank you to those that suggested some. At this point I just need to decide whether I should devote my undergraduate experience to research, or save some time for running.
I understand what it is like to train with the best of the best and I often find myself with better training results than those people, but when it comes down to it I probably am not that suited for that competition due to chronic anxiety, short race distance (5k) problems, etc. I think that is why I enjoy marathons so much. I should mention however that I do have a history of stress fractures and other injuries when I was putting in upwards of 80 miles a week in. There is still a weird part of me that loves running that far and maybe it would be best if I just did it independently in college or for the Boston Marathon. BTW I was going to go to a qualifying race the day before Boston registration but it was canceled 
As for track there is still the option of joining this year. I guess I disagree that long distance runners cant be good sprinters. For me its either under 800 or over 10k and I am flying. Don’t know why but thats just how my cardiovascular system and legs work. However, I can’t do both at the same time. My only problem with track is that I haven’t trained with a team in a few years and might be rusty on drilling and the pace of things.
If anyone has experience with D3 XC or Track and how it affected their academics/internships, and what level of training was expected from them that would be appreciated.
Junior PR was a 17:08 for anyone that was wondering
Also for people worrying about admission stats I am actually from Idaho but wanted to go to college either in California (where I grew up), or ruralish New England (because I love forests). Do you guys consider Idaho to be underrepresented in those schools? Also I am a white male, but my liberal life experiences (grew up Mormon, now agnostic) and activism might help with fit.
I’d give HS track a try this spring to see if you like the team structure. Sounds like you prefer road racing and training on your own, which is fine.
I wish you the best and keep us posted. My D2 is late in the game and didn’t start reaching out to coaches about running D3 until late fall (she’s a senior). She does run track and xc at school is more of a mid-distance runner.
We have another D in college currently so we reluctant to have her apply ED and so she has spread a net at several schools and visit NE colleges after learning if/where she gets in. She has been offered a few OV but can’t convince DH that she should go see some beforehand.
Hopefully, it will all work out for you. Even if you don’t get recruited, you can enjoy your life long passion of running!