A good cover letter, can help the person receiving the resume, see why you are applying. Here is a good article, with many links to help you not just with the cover letter, but with the resume. It's from Forbes.

You mention it's not the average job nor application process, and for mentioning that, I feel, a cover letter would make this, not your average resume

Hope it goes well!!

<quote> ...The first paragraph lays out the specific job you want and, in the best case, names a mutual acquaintance... ...In the next paragraph, write a short summary of your career, tailored to fit the company you’re approaching. In the third paragraph, lay out several specific accomplishments that are relevant to the prospective job. Wendleton likes to do this in bullet form. Put your most impressive accomplishment first, she emphasizes. In the fourth paragraph, say when you’ll be getting in touch...<quote>
How To Write A Cover Letter - Forbes