ISO: Baking with Soy Flour

My husband is severe diabetic and I am a baker and serious breadmaker of long standing. His doctor wants me to use only Soy Flour (and no other flours) and he wants me add BENEFIBER to the dough. Does anyone have some good recipes for breads and cakes? I'm thinking maybe sourdough too? Perhaps that will give me a better rise. Given Soy Flour already has a lot of fiber and I'm adding fiber, rise has been a problem. Any suggestions for adapting my current recipes over to soy flour with additional added fiber would be helpful too.