A decision on an "Escrow Waiver" is going to be made from lender to lender. You definitely cleared one hurdle by putting 20% down but the exception will also need to be made based on the credit score, assets, Debt-to-Income ratio, etc.
You will need to note, however, that the monthly tax and interest amount will need to be used to qualify for the loan regardless of if you pay it monthly or not. I do understand why you would want to do that though. If the tax assessment is based on the prior sales price then obviously you would get stuck with a higher tax assessment until the county revises them based on the new sales price. I heard they are working on a way to correct this to try and help more people qualify - but you know politics.
If you would like to qualify and see about the escrow waiver, please feel free to call me. I should be able to get an answer within minutes based on what the system says. Call me if you have questions.
Bank of America Home Loans