Not sure if this would help in your situation - Security First Network Bank (an online bank) has a Visa card that earns "Secure Miles" (i.e. points that must be used in their travel agency program, 25K for a RT domestic ticket). The reason I thought I would mention it is because using the Visa card you would have the protection of using a credit card vs. a debit card and the way their online banking system is set up, when you log on you see all your accounts on one page and you can transfer the money out of your checking account weekly to the Visa account to avoid carrying a balance or managing your money that way if you choose. FWIW on a seperate issue- when I opened my account with them in 1996 they only allowed a $500 opening deposit to be charged to a credit card, so didn't want anyone to get excited about earning miles for opening an account with them, they seem to have that nailed shut
Personally, I prefer to use a mile earning credit card vs. a debit card for the reasons stated above plus if you return something it takes longer for the credit to come through and the purchase does not have the credit card "protections" attached to it either.