Good for you on the prenuptual. Only problem I see is what good does it do YOU for her to pay rent on a place she is not staying? If she is staying with you she should be helping YOU with the bills even if she has her own or others. She needs to manage it so she can help NOW or she will always have excuses why not to help due to her other bills.
Im being nice by watching out for my other fellow board members.

Not trying to be a dick, I realize you think you are doing what is smart but take a step back and really look at it more. Ask your attorney not only what you should do to protect your assets but what HE would do or your fiends what they REALLY think..