My situation is almost exactly the same, and based on the research I did there are two ways to look at the situation.
1): At this stage it is called micro mets, which is undetectable by a psma-pet. however it is some place in the body. At this point it is very vulnerable to systemic treatment such as ADT and or chemo.
2): The other option is to wait until it "ripens" to the point where a psma-pet can see it and then hit it with pinpoint radiation.
Hope that helps.