Don't forget that outdoor cable oftentimes has a metal strength member in it so it can be run from poles. The underground direct-bury kind of cable has metal armour for rodent-proofing and protection when the ground settles. Just because it's fiber cable doesn't mean you can forget about lightning protection and proper grounding. If the airwaves aren't too congested wireless might be a better option here.

You can always blow metal-free fiber in pipes. I'd use PE pressure pipe of suitable size, pull a string into it with a vacuum cleaner and pull fiber in... Hopefully the fiber survives.

Joburg :)