After a copple of tries with Ubuntu that failed to be persistent, and the hint to create a fresh question form the community to find I easier. I am try a new attemp. My Goal:
A USB stick live system with a boot partion (for kernel, grub, initram, etc. (ESP part as /boot(/efi)) ) a partion with the read only basic system a writable partion with addional software like gcc and the setttings, so keyboard layout stays the same even after I took a break and shut down the system optional 1 GiB Swap, not sure if it is realy needed but informations about the usfulness of swap are conflicting)
The system I am using to test the perisistence with has a skylake processor so the system should bring at least a 4.3 kernel.
I wish a step by step how to as answer (distribution used is not importat as long as you stated it) Goal is to crosscompile a LFS system on the target with the livesystem (don't ask why, I want to learn something, and I figured it would be best to use a livesystem for that) .