Mostly "nothing", "what they bring with them", or "what they can steal". Which of these is the most viable option depends on the length of the trip.
You don't.
The Stowaways - 2012 is rated/received certificates of: USA:G
The Stowaways - 1949 was released on: USA: 1 July 1949
The Stowaways - 2012 was released on: USA: 3 June 2012 (video premiere)
Stowaways and Strategy - 1917 was released on: USA: 31 December 1917
The cast of Stowaways and Strategy - 1917 includes: Lucille Hutton Joe Rock
The cast of The Stowaways - 2012 includes: Nick Brocha as Stowaway 2 Ernie Vigil as Stowaway 1
Call of the Wildman - 2011 Savage Stowaways - 3.9 was released on: USA: July 2013
runnaways or stowaways
The plural is 'stowaways'.
Monsters Inside Me - 2009 Stowaways 2-6 was released on: USA: 28 July 2010
physical laws involving fuel and weight.