that an eeePC? (sounds like a 901, that had a 4gig primary SSD, and a 16gig secondary SSD for the Linux version or 8gig for the windows version)
I found with ubuntu and mint etc, that realistically I had to put / on the primary drive, then split the secondary in to 2 partitions. typically /home on most of it, and iirc /var or something on a spare 1-2gig of that (otherwise every time you do an update the primary SSD runs out of space downloading files).
personally, I’d back everything up, and start over whenever i did an install (didn’t keep all that much user data on it, and much of that was dropbox, so add that and all the files resync anyway).
ubuntu, mint etc. end up using about 2.8gig of the 4gig iirc for a default install.