I'm so sorry to hear what you and your family are going through, SD Mom
There is a section with resources on finding the right facility for your family here:
https://bpdfamily.com/message_board/index.php?topic=114267.msg12588412#msg12588412Depending on his age, you may find that Blaise Aguirre's book, BPD in Adolescence is also helpful. If I remember correctly, there is a chapter on inpatient/RTC facilities in the book, too.
You may want to see if there is an NEA-BPD Family Connections chapter near you. It can be hard to locate someone, but keep working at it, and see if there may be facilities nearby.
I know there is also a site that charges $25/month to talk to a consulting service that helps you make sense of what facilities and treatments are out there, reputations, how their business model works (insurance, no insurance, etc.) I'll see if I can find the site. I haven't used it, so can only share a link to let you know it exists.
In the meantime, if you are looking for good reading material, Shari Manning's Loving Someone with Borderline is a great starting place.