the club here in Raleigh that is affiliated with Medicare is Healthtrax. I looked them up; there are many around the country. It seems to me that they are operating like a regular gym in many ways; check whether there is one near you.
Clubs are always in need of instructors. I cannot imagine that it would be difficult for you to get in, particularly considering your credentials.
You might want to do a little research into American Specialty Health. Their website is www.ashcompanies.com.
Hope this is of help to you.