So, just to update, we have bought a Resmed Mini, which can operate on both 230 and 12 volts, plus a battery big enough to run it for two nights, which can recharge from both 230 and 12 volts. The unit is approved for use on planes. It has auto start/stop and other features. Using a nose prong mask. Very happy with it. And The Navigator is getting a good night's sleep, so happy wife = happy life.