i had a idea very long time ago which was almost the idea of a full iso.
Slitaz should comes in 2 parts embedded in a single ISO : A will be unpacked into RAM after boot (like the live system) and the other part B would be already uncompressed onto the USB (so not loaded into RAM).
The part A will be small and contains all the vital packages, the second part B will heavy and contains all the packages of leading softs like LibreOffice, Blender, etc ... with the purpose of offering a full desktop.
The part B will have its dependencies connected to part A
The live-user would be able to install and test additional packages like he can does now, and they will be added into the part A (so, in RAM). For stability purpose, the part B will be like a read-only system.
All the drivers and firmwares will be included in the part B in order that the system can pick up the right drivers for its own hardware.
--> The goal is to minimize to it's best the time between the download of Slitaz and a full Slitaz experience as a full fast desktop on a single usb key