Actually, you only need 34+ CF to get Liedel and need to have less then 60 for Sheen. Don't forget to visit that town with the little girl in Ausra Plains!
So in a low CF game, to get both, just do Sable Lowlands before Audvera Heights, giving you a +15 CF, easy enough for Liedel. And then just capture everything and it'll be plenty low enough for Sheen.
Worst case scenario let the enemy capture some of your towns lol.