Difficult to say as it depends on the region and distances you are going to travel. We often do this for a couple of weeks with the longest trip being 2 months,

Difficult to say as it depends on the region and distances you are going to travel. We often do this for a couple of weeks with the longest trip being 2 months, while traveling from Northern to Southern Europe where we spend the winter at a rental villa. Biggest cost is the occasional hotel or apartment to freshen up. Otherwise just fuel + food.