Eee PC 901, what to mount to secondary SSD?

Hi, everyone. Basically what it says on the tin. I'm trying to get Ubuntu 15.10 x32 on my netbook (it currently has 11.04(?) installed from way back when). It has a 4GB primary SSD and a 32GB secondary SSD. I'm doing a clean install, but the install keeps erroring out because there's not enough space on the 4GB drive. I've mounted /home to the second SSD, but what else can/should I mount to it? I want to keep any core/boot-up files on the first drive because it reads/writes much faster than the second. Right now my thoughts are to move /usr, /var, /tmp, and /dev. Thanks!