Hi Julie,
If the traditional mortgage route isn't working for you there are definitely companies out there who will qualify you based on the property's debt to income ratio instead of looking at your personal DTI. Without knowing all of your details, i think something in the 7% range sounds like the right ballpark for those types of lenders. Their rates are higher than traditional lenders but they are willing to be more flexible with their underwriting. Most will probably want to pull your credit at some point, but not necessarily before giving you a rate estimate.
To get a rate in the 4-6% range from a bank you would probably need to talk to a local bank or credit union who is comfortable holding your loan on their balance sheet. If lenders are telling you you're over-leveraged, it probably means that you're too leveraged for them to be able to make the loan under the guidelines of Fannie or Freddie (or whomever else they plan on selling your loan to).
I hope this helps and feel free to message me if you want to talk further or have any questions.