I recently bought a songbook so that I could do up an entire album by a band, and I've come across a lot of notes that are meant to ring out, without sustaining those played over it. Does Rocksmith support this feature, or is it not yet doable in EoF?

It's been doable from the beginning of RS customs.  In EOF, if you give a note "crazy" status (select it and press the T key), it is allowed to overlap notes that don't use the same string(s) as the crazy note.

Oh, okay, great! I had no idea what that function did to the note, so I sort of ignored it. Probably should have tried all options first. Thanks for the tip!