I have been away from this forum for awhile and return to find a lively discussion on this topic.
I'm both a licensed psychologist and a board-certified family psychiatric-mental health (PMHNP) nurse practitioner. I practice in an independent state for NPs and am in full-time private practice; I incorporate both roles (psychologist & NP) on a daily basis.
One license does not take away from or prohibit the actions of the other. I practice completely autonomously and independently in every aspect and have no required collaboration or supervision of any kind for any and all aspects of practice.