If that works, boot into sysmaint and append it to the grub-live entry. Then when you boot from your Kicksecure USB (ideally with no internal drive connected, if you want to be absolutely sure), establish a WiFi or wired connection first, then yank out the USB. At that point you’re fully in RAM with no media left to write anything to.
Again if it works it depends on how much RAM you have and what you’re running (RAM exhaustive apps), you should be fine for most tasks. But if you’re dealing with transferring files larger than your total RAM? Yeah, that’s not happening, it’ll just crash.