Why ask for help and opinions if you are unwilling to listen?
10% is not enough. Everyone has told you that. If I am a private lender in California, and I can make 10%, PLUS 4 points up front, lending at 65% LTV, and have borrowers lining up at my door, why should I go with your project?
Are there other real estate investments that could yield more than 10% COC return? Absolutely! Tens of thousands of them!
Look at it this way. What are you bringing to the project that an investor cannot get cheaper elsewhere? The answer is the lead, on the the property that your landlord may be willing to sell you at a below market price. Your husband as GC? Why wouldn't an investor simply hire a GC, and end up paying for less while having complete control?
"We would like to do this project not as a 50/50 split between us and investor, but just as a straight interest rate of return of 10% for the investor. Did I answer that correctly?" You answered it correctly, but Steve wasn't asking a question, he was giving you a suggestion. Specifically, that an investor would not be interested in 10% interest, and that if you want to find the money, you are going to need to do something like what Steve suggested, and take a share of the eventual profit. A share that will almost certainly be LESS than 50%, by the way.
Steve was suggesting that title searches on similar projects would reveal the names of the investors involved in those projects, and provide you with a list of people to approach.