You should be able to do that with no problems - I set up an SD card to boot into Mint 18.3 last week and installed VCV Rack onto it (it won’t run on my current 17.2 desktop) and it seems to have kept the settings just fine.
As far as creating a USB stick, what OS are you using currently?
You’ll need to either install the Mint 18.3 ISO onto a USB stick using some other OS (which of course might not be possible for you right now) or I think you can run an install > USB stick/SD card etc from the live CD.
I’ll try booting up from the Mint 18.3 SD and see what it says.
Also, how did you make or obtain the Mint Live CD?
In UNetbootin you should see an option named
“Space used to preserve files across reboots (Ubuntu only)”.
This will give you persistent data space on your usb-stick.
Maybe a look to this link will help:
Its a bit older, but for me the information still looks valid.