If you are going to use an LLC, then you would have to give up equity in order for your cash partner to be considered a member. As pointed out earlier, a loan to the business is different from ownership. Something greater than an 8% stake in the equity may be able to spin off the required rate of return. You can back into that number based on your projected NOI. But, there are so many risks to the cash partner that just giving them the equivalent of an 8% stake in the property would not be enticing enough to attract the investment. When you listen to other investors that raise large amounts of capital they usually have a track record of success with their particular investment offering. I could see a few options that may sweeten the deal for a potential investor.
1. If one of you held a CPM designation and preferably had some years of experience backing you. That would help in terms of you actually bringing something, other than the deal, to the table.
2. Give up significantly more equity with a provision in the operating agreement where you could potentially buy-back equity from the other partner (possibly at a premium). But then you may be looking at regulatory issues there if you offer more than one type of shareholder class. So make sure you have an experienced RE attorney guiding you. Your cash partner will.
3. Sell the investment for a small equity slice, in lieu of cash, to an investor that has experience with owning and managing a property like the one you are describing. Many articles here are written by experienced RE investors saying the same thing; you have to bring something of value to get an education or investment (cash). The cashflow and equity may be smaller, but the benefits are stacked more evenly for all parties involved.