I would advise relying on remote opening just incase the battery goes dead. As a short term measure I would suggest you switch the barrel from the passegner door to the drivers.
Also (thanks Moonwrap) Mazda can produce you a lock barrel to match your existing Keys. This is done by using the number etched onto your key, there may be a short wait for the barrel to be made though, its expensive either. Moonwrap says they did it even for her Cabriolet which is JDM, so it should be pretty simple
Changing/fitting the barrel is not hard either, just remove the door card and everything will become clear