I was living in rural West Virginia when I needed to take on the trans-beast. My first attempt at finding any sort of support was contacting the local college (40 miles away. dead end basically). That was followed by Psychology Today's Doc Find which has a Gender Issues tick box. Still the closest was some 90 miles away.
The best way to find a therapist that is T-Friendly is through a "Local" support group, or perhaps some county or state LGBT organization. If you want to try looking for a therapist near by, you can always call their office and try to arrange a 5-10 minute phone call with them to discuss your issues and their experience. I haven't called any that weren't open to that.
If you are in the boonies and in search of the HRT CYA letter, your biggest roadblock may be finding an endo or GP willing to take on a trans client. Depending on the Doc, some may want the permission slip written by someone qualified or experienced with GD. Where I was living there was only one, some 100 miles away. Most of my group members used that one or went to Whitman-Walker in DC.
When you get right down to it, any doctor can legally prescribe any drug. The decision to prescribe HRT comes down to their personal feelings and mainly lawyers, I mean Mal-Practice Insurance. "Informed Consent" is generally what it is called. No therapist needed. You're likely not going to find anyone doing that in the boonies. Except perhaps you old family GP.