Oops, didn't read you post fully. There could possibly be a difference between vouchers/travel credits and miles. It probably depends on the amount, but if you had a 20k refundable airline ticket, I doubt you can just pretend it doesn't exist. You would see a cottage industry built on helping people hide money from the bankruptcy trustee that way if it worked.

Each state has a list of assets that are exempt from bankruptcy proceedings (stuff you get to keep.) I doubt miles or airline tickets are listed explicitly, but that would be a good place to start looking.