Then, if I win the contract, you will act as my bank. You do not send the money to me at all. You wire the money to the title company and put a lien on the house I purchase. I will spend the money to renovate the house. At the time of the sale, your principle and interest will be paid first, and then the left over will be mine.
This is already safe enough for you. If you are still not comfortable, we can have an agreement signed with a public notary that if the house is sold at less than the fund you put in, we will pay that difference to you so you have no way to lose anything.
I know the local market so well that I have no way to lose anything, even if the market goes down 30%. This is actually a win-win situdation.