Yes, Oregon Health Plan covers Top Surgery!
OHSU has two surgeons doing Top Surgery, Dr. Berli and Dr. Hansen, but the wait list is about 1.5 years right now. Might be worth getting in line though.
Dr. Thakar in Portland and Dr. Manders in Coos Bay take OHP.
Dr. Stiller is now in Spokane. I could be wrong but I don't think OHP pays for out-of-state providers because there are surgeons in OR who take OHP.
Because you're using insurance, two letters will probably be required.
There are three therapists in Portland who don't charge for letters:
Stacy Sheffler, LPC
Rosanne Marmor, LCSW
Nicole T Prophet, Licensed Professional Counselor intern (online sessions available)
I hope this helps!