I think you could say that the 300 hours is probably clinical, although the fact that you aren't necessarily really seeing your mentees as they interact with medical staff might be a bit sketchy. For your current job, is your consenting/enrolling done in person? If it was, I would say it's clinical but some schools don't look too fondly on clinical research being clinical so YMMV.
With your stats, I would say that if you actually did another gap year where you could find clinical volunteering or found a clinical job before you submitted AMCAS so you could project hours then you could honestly shoot for T10 schools. As you are now, you could probably squeeze out an acceptance to a mid tier school at the very least if your writing is good and you can really describe your 300 hours in a clinical light.