I was wondering, what stats did you give the hitchhiker or rest...of im i overlooking it?
This adventure is system agnostic, so The Hitchhiker has mechanics to influence gameplay but no system related stats. If you are using the micro-rpg, Instant Horror, in the back of the book there is a table for improvising monsters stats. All the rolls are player facing in that system, so you only really need to figure out how much HP you want the monsters to have.
Hope this helps, let me know if you have any more questions!