Quote - I know I can parent everything to the ground (and then rotate the ground) but there are sooo many objects.

Perhaps you are looking at the problem the wrong way? You say, quote:

But  I just realized that I was looking at it wrong, and i made it sideways, and now every time I use a standard pose, the characters are facing the wall. :(

You have too many props, but do you have too many figures. Instead of turning the whole set round by n degrees, what about if you rotate the Body actor of each figure by n degrees?

A properly made pose will not rotate or translate the Body actor. So if you only use properly made poses, everything should be sweet. Unfortunately not all poses are properly made, but you can overcome that problem too by locking all the Body actors after rotating them by n degrees.

Of course this solution assumes that you have a lot of props in the scene, but not many human figures. If there are a lot of figures in the scene, this solution is not as good, though it may still help a bit.