I want to create an USB stick to carry my Ubuntu everywhere around with me. It's not intended to spread Ubuntu by installing it everywhere, but rather for running my configured system on any computer I come across. So far, I went with installing Ubuntu with unetbootin, however, I have some issues with this. When installed with netbootin, the original disk image is kept intact on the flash drive, forever. Also, a file is created for persistent storage and during boot it is accessed together with the image by overlayfs. This, in my opinion, has the following problems:

• If system is updated regularly, then files from the image are overwritten in persistent storage, doubling their size and wasting precious space.
• Persistent storage has a fixed size that you have to define from the start, again, wasting precious space.
• I'm not 100% sure, but maybe using overlayfs makes disk access slower, and more so on the relatively slow devices.

So I'd like to find another solution: either to get rid of the original image or to install Ubuntu "normally" on the separate ext2 partition, or maybe even install it in the main vfat partition on the USB stick. Suggestions?