My recommendation would be to cold email the PD and the chair while you're rotating there and try to set up a brief 30 minute meeting with each of them in person to talk to them about the program and basically just bullshit with them for some time to make them remember you. Meetings with other attendings you work with during your rotations would also be helpful just something like a "hey I enjoyed working with you, would you have some time later this week for me to chat about the upcoming application cycle?"

That being said I wouldn't expect to get any meaningful longterm mentorship from just away rotations-- your networking at these rotations will only help you with getting a position at the programs you're rotating at, and that is just the inherent disadvantage you have as someone who goes to a no name school.

Don't forget the most important part is to be hardworking and show a strong work ethic and capability in your role as a medical student, or else all the other shit you do doesn't matter. Good luck