You mentioned Trauma or Cardiothoracic Surgery ICU as areas of interest:
One program I am aware of that actually allows outside students (non-affiliated students) to rotate through is this one:
Nurse Practitioner Student Rotations - Education - UM Shock Trauma Center
It's in Baltimore so I am not sure how that fits with your ideal metro area but this team (not the NP alone) is well regarded as experts in Trauma.
I used to work in a 16-bed Cardiothoracic Surgery ICU in the Midwest at a large urban medical center that has a medical school affiliation but no specific nursing school affiliation. We had ACNP students from 2 different local programs. Not sure how that is set-up now since I've been away. Again, not sure if the Midwest is where you want to be.
My current practice involves rotation through Medical, Surgical, Cardiovascular, and Neuro ICU's. There are 62 beds total. We are not the designated trauma campus of the university, hence, we do not see trauma patients. We have a group of NP's providing 24/7 ICU management. Unfortunately, I've never seen students from an outside program. The students we precept are from the university ACNP program we are affiliated with. Even the medical students who rotate and actually touch patients are students from our university. Once in a while we get "guest" medical students from another institution (all over the US actually) but it's usually just a few days of observing and following with attendings to explore an interest in residency at our institution.