A working NP applying for per diem RN position

I can't speak from the point of a manager who would review it, but from a chronological order usually you start from your current or last job working back. Either way, they're going to realize you're an NP when you list education, on a license look-up, or explanation for the time between your last RN position and now so I don't think changing it will make that much difference. Might as well state it up front.

From the messages that I have read here, I've noticed a lot of people have struggled to find employment in the past few months so it may be completely unrelated to the fact you're an NP.

I would look first at your cover letter and maybe look to see if your reasoning for wanting to take this position could be more clear or appealing because they're going to wonder why an NP would want to take an RN position. I've considered it myself because I really miss bedside nursing at times as crazy as it sometimes was. It's just putting that into words to get HR and hiring managers to understand it too.