[d0ntjump]

I've done this with Kali and other distros. Do yourself a favor and take your ssd/hardrive out of your machine to eliminate any confusion with partitioning. Run the installation like normal and then just choose the USB for the installation. It will work like any other mass storage device. I do this all the time with SD cards too. Hope this helped.

I just keep a rule of thumb to never fuck with /dev/sda unless I'm in a virtual machine, it hasn't failed me so far.

I hear ya! I'm just one to play it safe.