Disk image of a full install of Mint 19 to a USB device

[elvino1]

I have read literally hundreds of posts of the full installation of Linux Mint to a flash drive and it seems to me that the primary culprit in correctly booting the uefi flash drive is ubiquity. No matter what I do, ubiquity writes to the internal hard drive of my computer, the boot record during installation. The solution offered by some is to disable the internal hard drive but this seems to me to be a sledgehammer fix.
Why is not possible to have a downloadable version of Linux 19 as an .img file that would install when unpacked on to a usb stick, complete with all the correct boot records? Or have I misinterpreted the situation?

[HaveaMint]

Select-New-Partitioning-Table.png

Down towards the bottom of the pic are you selecting the device for boot loader installation correctly?

[elvino1]

Yes and I believe I have been following instructions very carefully. I know I am not alone as this and other forums are reporting the problem of ubiquity writing to the internal hard drive. In my case I want to be able to boot a portable usb drive to a variety of other machines. If I remove the uefi partition from my internal hard drive after attempting to make a standalone usb drive then the usb drive won't boot at all. If I leave the uefi partition on the internal hard drive the usb drive boots justs fine - but not on any other machine.

[Laurent85]

You may install in Legacy mode, computers you intend to use need to support Legacy boot. Or create a Live usb with persistent partition, solution I prefer over full install, live stick can boot in both modes.