Cover letter for NP seeking RN position

I am currently working as an NP (due for first ANCC renewal next year), and am looking to change gears and leave the NP role behind.

There is a job as an RN care manager that I am thinking of applying for... however, I am concerned that they won't consider me because of my advanced practice certification. I am thinking to address this concern in my cover letter.

My idea is that I could just not renew with ANCC next year, and explain this plan in the cover letter. Does this strategy make any sense, or should I not say anything about it at all? If I do address it, is the cover letter the place to do so (vs hope for an interview to discuss it there/then)? If the idea is not totally off the wall, how in-depth into my reasons for this career shift should I go in the cover letter?
It is not unusual for NPs to be working in non-NP positions, at least in my organization. One of my nurse educators is an FNP; discovered that she preferred this environment to working as an APRN. My advice? Don't make a big deal of your credentials. Focus on your work experience instead.