Do not blindly paste commands from this guide, you're responsible for any destruction it causes.
This is a guide for installing a minimal arch linux from scratch.
This guide uses full disk encryption with a detached luks header so if you were to lose your laptop it's impossible for an attacker to brute force one of your luks slots. This works with any generic USB storage device.
The main threat I'm trying to mitigate is someone stealing my laptop from my backpack while I'm out and about. I can rest easy if my laptop is ever stolen knowing that it's nothing but random data on both the backup disk and the root partition.