It's great to hear that they are doing this.
When I got out of college, a friend and I took a 2 week trip to Florida from Buffalo, stopping at many places along the way, in my 1976 AMC Pacer. We slept at a rest stop once to save motel costs. We had no air conditioning in the car. We came back home with just enough money to pay the last toll in NY! This is one of the most memorable trips I ever took.
I am glad they are doing this instead of spending their time texting back and for to each other from loxcal malls. Too many young people are wasting this time of their life. This is one of the few times that you can do this before job, family, etc puts up restrictions to it.
A life experience doesn't mean everything will go perfectly, it means that you learn to work around problems and setbacks, just like you will need to do later in life.
Whatever the outcome of their adventure, they will be the better for having done it.
Steve