How to install Zorin OS directly?

Not a boot from USB or CD to start the installer from a Live device, I mean skip the middle man and just create a Zorin-To-Go on a USB, External HDD, or SSD. Like a Windows To Go Workstation, but Linux, that's the only way I can explain it. I want to put Zorin OS on a external SSD without a need for a entire live CD/USB.

You could just clone an installed version to your external SSD using Clonezilla. However, bear in mind that you may not have success using it as a GNU/Linux to go workstation as the PC you attach it to might need drivers that aren't present on the SSD that was created from a different PC. It will also be dependent on whether other PC's have not had the 'Boot from external hard drive' disabled in the BIOS for security reasons.