You need to ask yourself how comfortable do you want to be? 2 women and a couple kids, you're going to want to carry some stuff to be on the road for a year. I would think trying to live out of a tent or even a popup or mini trailer would get old pretty quick if that's all you do.
My choice would be a used full size conversion van and a small travel trailer with bunks. Hard to beat travelling in a van with kids, I managed 46 states with my 4 over the years. Easy setup at the campsite, kids have their bed ready anytime, cozy in bad weather, everything has it's place. Everyone will need some space of their own at some point on the road that long.