Clinically, neuro-onc is in high demand so you don't need to promise to be a big researcher. Practically, a lot of the jobs are academic so you might want to express interest in a traditional niche - research, admin, and/or teaching. Think of it, to offer patients top-of-the-line treatment, you need to be in clinical trials or have the resources of a cancer center. Even still I think demand for the field is strong and there are a lot of centers that would love to have a neuro-onc and can't find one.