One idea I have: We treat it like a loan, that I plan on paying higher percent than she's charging. For example, she loans me $100k at 3% (which is more than she's currently getting on her $100k). I include it with my investments that I make 10% on. I then pay her back the 100k with 10% interest. Even if I make less than 3%, I still pay her back at least $100k + 3%.
Kosher? Not kosher? Other ideas of how I could do this?