Several people have had pre paid cards with them on tours I have been on. None of the cards worked.
You can get a travel pre paid debit card from AAA and other places. They key is it must be a TRAVEL card, not just a regular prepaid card as those do not work outside the US. Hoverer, the fees on these cards are outrageous. There is a fee for everything including just to get the card. Not worth it.
The best protection against unwanted access is to use a credit card (preferably one without any foreign use or conversion fees). If you get one from somewhere other than your credit union, there is no way anyone can get to your other accounts. Of course use your debit card to get cash from a bank owned ATM for the times you need cash, but never use your debit card for purchases. Similarly, use your credit card for as many purchases as possible but never to get cash.