Sure could.

You'll need two control panels and lots of RAM; I'd go with at least 64, or 128 if you can find the SIMM.

RamDisk+ has good support for booting off a ramdisk. It doesn't actually boot off it so much as switch-boot onto it, using a legacy feature from the System 6 days.

Sleeper is a control panel that can spin down your hard disk.

With both of these properly configured, I think you can get what you want.