We just got home from driving a motorhome pulling a car from Seattle to mid-Michigan. The trip is doable - we came across on I-80 and had to stay an extra night at a couple of RV parks because of weather. We found open RV parks along this route with full hook-ups including water coming from heated hookups. We do have heated tanks and wouldn't try the trip anticipating using your onboard water without some kind of heat for your wet bay. we had a few single digit nights on our way home. Be prepared to have to stop as they do literally close the interstates in bad weather and Oregon does require you have chains aboard. Keep an eye on each state's DOT website for road conditions. We found those to be extremely helpful. It is doable if you are prepared.