Ubuntu Precise Pangolin (12.04) Alpha on EeePC 901

I've been running Ubuntu 11.10 on this little machine basically since it's been available and never had any problems as is expected from Ubuntu.
Now with an alpha of 12.04 available, I wanted to upgrade.
One problem is that I have Ubuntu / partition of the 4 GB drive (ssd) of this machine and this partition was pretty full (3.75 GB of 4.35 GB available). To install this version requires free space on / of 1.25 GB.
To free up space I basically followed what's suggested here (none of which is new, but nevertheless is effective):
1. sudo apt-get clean
2. sudo apt-get autoclean
3. sudo apt-get autoremove
4. dpkg --get-selections | grep linux-image
will provide a list of installed kernels. Each one takes up around 100 MB. So, delete those you don't need (usually the oldest) with the following command
sudo apt-get purge "oldest kernel image" which will be something like
sudo apt-get purge linux-image-3.0.0.2-generic
5. Next I ran Bleachbit as root
6. Finally I used Synaptic Package Manager to delete Firefox and LibreOffice neither of which I use. In any case I can always reinstall them once the upgrade is complete.
After all of these space saving attempts I was down to 2.94 GB giving me 1.41 GB of free space.
7. Next, I updated my install with
sudo apt-get update && sudo apt-get upgrade
8. And finally, I started the upgrade with
sudo update-manager -d

However, although the upgrade proceeded without problem, the / partition filled to capacity and the upgrade stopped.
So, I rebooted to Ubuntu recovery but this stopped on "checking battery status"
Then, I used Ctrl+Alt+F5 to get a prompt and logged in with my user.
Then I ran
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get autoremove
sudo dpkg --configure -a

This latter went on for almost an hour, but when finished I was able to boot to Ubuntu 12.04 GUI
Can't say I fully understand everything that happened but at least it worked.
However, seems you need something like 2 GB of free space to upgrade Ubuntu.