Why don't you just try to work for the Dept. of Corrections? Lots of jobs available in CA. I'm sure that your qualifications would be more than acceptable, since your background is both psych and NP. You'd see lots of patients who are similar to the patients from inpatient units, lots of co-morbid medical problems, and you'd be able to hone your skills pretty well, learn new things, interact with and learn from more senior boarded psychiatrists, the environment and learning experience wouldn't theoretically be that different from a post medical school psych. residency experience in an acute inpt. psych. on a county hospital unit, plus you get the additional bonus re. forensic psych. exposure, etc...
Of course, if your goal was really to get the MD and subsequent private practice combining inpt. and outpt....this wouldn't be the road. But since you mentioned you want to learn more about psychosis and experience acute inpatient work...I really think Corrections would be a pretty comparable "shortcut" for you...The money wouldn't be bad either, from what I hear, although it goes by scales, so you might have a different scale on the PhD track vs. the NP vs. the MD tracks... Benefits are good...you could learn (fulfill your knowledge thirst, get additional interesting experiences, AND have a good retirement package too.)