Some Cornucopia-and-Dark-Ages-only kingdoms seem like they could be quite fun!
I suppose with Fairgrounds on the board you'll have an interesting decision to make from the very start. Do you trash your starting Hovel and Overgrown Estate or keep them for more Fairgrounds variety? Because without a Supply pile for them, once you trash a Shelter, there's no going back!!! Well, unless there's another gain-from-trash-er that can gain cards costing as low as (1).
Hmmm...7 basic Supply cards (VP, Treasure, Curse) plus 10 Kingdom cards plus 3 Shelters is exactly 20! You could get 8-point Fairgrounds without the aid of Colonies, Potions, Young Witch, or Black Market! And it might give another reason for buying a Curse, aside from piling out or Ambassador. (I'm assuming we still play with those purple cards in Dark Ages and that Ruins don't replace the Curse pile...?)