I wonder if when I am a fat old bald guy, if I will like hentai featuring fat old bald guys... Cuz for now, ugh. that has to be the demographic for this right? fat old bald guys?

I also have the same problem with my gf, only with the added problem that she won't read incest, which is like half of all hentai.

Here are some authors she is quite fond of (being that miraculously they seem to respect women)

1. Amatarou
2. Shunjou Shusuke
3. Sasagawa Hayashi
4. Mikami Cannon
5. Saki Urara
6. Tomohiro Kouda
7. Hidemaru (she loves boing boing teacher)

That should be a good start and you should be able to find most on this very site