We have never driven 12 hours in one day. The most was 8 hours and we left way early in the morning so that we arrived at the next stop in the afternoon or early evening. Driving an RV is more stressful and tiring than driving an automobile, and you need to be very alert because of the time it takes to stop it if anything happens. It can be done but we don't like to do so. We drive about 5-6 hours now that we're not in a hurry. I would try the 12 hours the first day to see how it goes but have your schedule flexible in case you change your mind.