We decided for not using ramdisk because we have to provide about six different ramdisk on the installation iso because of the different kind of machine that we support; so the size of the installation iso would increase very much.
Also loading ramdisk on some embedded platform is very heavy (think about efika).
If you need a temporary rw filesystem you could use /tmp (of course on /tmp is mounted a tmpfs!)
But, why should you use a temporary rw filesystem while installing cruxppc? Isn't the installing procedure suggested on the handbook good for you?
The cruxppc's keyword is orthodoxy: