The Littlest Hobos?

At around 20 mm high, perhaps they qualify.
A couple of days ago, I blipped Euan with his nose right up to the train as it rumbled past him. This is what he was looking for so he could wave back.
While the railways have always attracted a few who wished to travel but not to pay the fare, in America during the "Hungry Thirties" these hobos found all manner of ingenious ways of hitching a ride without attracting the attention of the railroad police ("Bulls") whose methods were frequently very brutal. These two are in absolutely no danger there!