The spread between "conforming" loans (less than $417,000) and "jumbo" loans is at historic highs, between 2-3%. This is reducing the number of potential buyers of expensive homes, resulting in a very high vacancy rates. In Nashville, for example, about 2.4% of the homes are for sale and vacant.
If you try this, use the FTC-designed disclosure forms to shop for mortgages. Here is a blank form. Try asking a bank for a combination conforming loand and a second mortgage that your bank would hold in exchange for keeping your demand deposits in the bank.