Maybe we're a little backward up here

but the island I live must have some of the most challenging fencing ground on the planet and in twenty odd years I've never seen anyone use an auger. I don't even know any professional fencers up here that posses one

I've seen miles of deer fencing done much of it dropped in by helicopter and apart from the odd rock drilling.
it's all been done with a spike and post rammer

With the strainers holes dug with these.

Seriously I know four guys who do this for a living over the most inhospitable terrain in Scotland and an auger is not in their tool kit.
Good luck, Paul