I think that any service organization would be a good place to start. I feel like I'm in the same boat as I'm also am a peace time vet. I've been going to the VA for over 20 years and I feel the same way, but I also know I need the care.
When you were in the service did you go on sick call? If you did you might want to request a copy of your service medical records. They might help you establish a claim. It might not hurt to just go to the VA and apply. I was hoping someone else might reply to you. I'm not that much of an expert but I can give you my two cents worth. I was discharged from the Army in 87 and went into the VA system for my knees. Now I'm trying to get my AS covered. My pain is mainly in my hips but it's geting into my back. The VA didn't even give me an exam for my hips so I've gone to my family doctor to get a statment saying that AS is conected to my Army service. That my be an avenue you need to do as well. If you have a statement, it helps to establish a claim. Hopefully someone else will post on this as well.