So, I followed options on Custom installation | Qubes OS
And I did manage to install bootloader on a USB 3.2, for some reason USB 2.0 won’t work for this. However, I could not set the Device type to LVM thin provisioning, it was greyed out at standard partition. And I also didn’t made swap as I have more than 16 gigs of ram.
So, now if I connect the usb 3 device, I can dycrypt sda3, partition where qubes is installed, and use qubes as normal. No sys-usb though as I have only one usb controller.
Is it good enough? I mean via anonymity point of view. Or is there something that I missed?
By the way, your tutorial returned an error, probably because of usb 2. But then I didn’t try with usb 3.