I had some simple requirements for the books:
1) No conjurations
2) 60 spellbook points or less
3) No more than 2 of any card
I've made Apprentice books using these same rules before plus:
4) No Familiars or Spawnpoints
The Druid really suffers under these restrictions because she is normally so conjuration heavy. A viable Apprentice book can be made for her, but it no longer feels like a Druid is supposed to feel if you ask me. Is pretty much the same as the Beastmaster at that point.
I haven't had any trouble making a Forcemaster book under these restrictions, although it does tend to be a little more limited than other books because of the lack of creatures. I'm not sure if this would really hamper them doing well, however, as Apprentice games seem to be won by whomever is most aggressive more than anything else. So, more focus might actually help to spur them into action. It also does a fair job at simulating the full Forcemaster experience, since they always have few creature options.