Not speaking from experience, since I haven't really started any physical transition or RLE, but I was looking into the requirements outlines by Dr. McGinn to try to get myself started on the right track with therapists, etc., funds withstanding. They don't both have to be doctors, so if Dr. Eli is an actual doctor with a PhD and apparently has experience with gender identity issues, it sounds like he'd be fine to write the "primary" letter. The other could be from someone with a lesser degree or medical license, perhaps even someone who works with your doctor. From my understanding, the "secondary" letter doesn't have to be from someone who's with you during your entire transition, just someone who is able to back the opinion of your primary doctor.