What is a way to have a co-signer on a loan without them being co-owner?

We have a friend who is much more comfortably off than we are and who is willing to co-sign for us to get a loan, since we will get disability and life insurance in the event of some mishap...but she does not want to be co-owner. She just wants to satisfy the lender that she will pay if we don't in order to help us get the loan. Small business owners, our tax guy writes off everything that is legal and true. If we changed our way of paying taxes we could not buy a home anyway. We are among those people for whom stated income loans were created...and it seems we are paying for the dead beats who lied and then defaulted. We can prove what we can afford but that doesn't help any more. The fact that my credits scores are excellent and that I pay rent that could be a mortgage payment doesn't help either, so our friend wants to co-sign for us on the condition that she not be co-owner/responsible for the property...but soley for the mortgage in the event we should default- which we won't, since we will be insured.