I just had a breakthrough a second ago and immediately wrote down what I did so I'll hopefully be able to remember it tomorrow. Maybe it would help someone else too.
I don't really know how to explain getting to the point where you are "using the voice behind your normal voice", but starting at that, I found that I need to pinch my vocal chords for a much higher pitch than I thought I needed, just enough that I was able to feel the resonance in the back of my nose (felt by touching the sides of my nose at the back). With more volume, you can feel it without touching. Then from there, I talked like I was really super excited about something and voila it actually sounded female in resonance and pitch. Note that by really super excited, I don't mean breaking into a falsetto. Super excited like I started fluctuating my pitch while speaking.
Also worthy of noting is that it sounded fake to me in my head, which is why I've avoided it all this time, but it sounded fine during playback when I recorded it. I also found that it sounds more feminine when I just say stuff off the top of my head than when I try to read it. It's like I'm trying too hard when I read and it's making it sound like a guy. Unfortunately I've been practicing all this time by reading wikipedia articles!
Not perfect, but definitely a starting point I can live with. I'd imagine once I can get that right, I can probably safely lower the pitch a bit to be less pinched and achieve the same results.