I quoted what is on their website. You can check it out. Rob is a carpenter. Maybe he misunderstood what you were asking. No upfitter puts black and grey tanks inside the van and there are very few instances of freshwater tanks inside. I can tell you my first week with an ARV van in 2015 I went a full 7 days with constant below freezing weather day and night and boondocked the whole time caught in a polar vortex in January culminating in an overnight in a Walmart parking lot in Gallup, NM that got down to zero degrees. My new ARV which I haven’t gone through a winter yet is better. ARVs are all lithium ion batteries of over 400ah with second alternators and the heating of tanks and batteries are all 12V directly off the batteries and it doesn’t take much and you drive just about every day which most do in cold weather and stop with batteries topped off at 100% SOC. Heating and hot water comes from Rixen Espar diesel-fired with glycol heat exchange.

Hi Dave, I called Advance RV and spoke to Rob. I told him I was unhappy that my Airstream Interstate 19 was not at all a 4 season camper since the lines and tanks were exposed below the coach. I asked him if the Advanced RV class b motorhomes were 4 season campers. I do not remember everything he said and I do not want to try to specifically quote him, but I was left with the sense that unless all the tanks were inside the coach and really insulated, they should not be considered safe in freezing temperatures. Clearly if you are camped with electrical hookups and ran the tank heaters, you might be ok. I was concerned about traveling from one spot to the next, with the frigid air blowing on the tanks and lines. I have emptied my fresh and grey tanks, used a compressor to blow out the lines, and will use the toilet and flush with a combination of water and anti freeze. I will use the camper as a travel vehicle and stay in hotels. Jerry