The problem you have is that most gas engineers are not LPG qualified so i would recommend taking it to your local caravan sales/repair centre whoes engineers should all be qualified and see if they could do it for you.
yes u can drive with the gas on the only problem is it could cause a venturi effect and blow out the pilot flame,but that ok cause once the thermocouple detects no flame it will active the shutting down of the gas valve within 40 - 90 seconds. CO2 detectors DO NOT DETECT A GAS ESCAPE they detect co2...