31Tundra not sure if anyone answered you yet. We don't have that model but the smaller. The two tanks are fine for us but I think the question is what you'll be using the propane for. Will you be boondocking, running the fridge going down the road, camping in the cold and using lots for heat and so on? We used it 5 nights to just take the chill off, heating showers for two people each day and hot water for simple clean up at the sink and it didn't make a dent in the two tank supply. I recall reading here where someone had a chart of a typical use of their propane. Maybe a search for that? Good luck and happy camping!