There is a rigid vang now, but when I sheet in the main the boom hits the top of the dodger. Can the rigid vang be adjusted to prevent that from happening?
If, when under sail the boom hits the dodger, something needs to be changed. But not the rigid vang. You should be able to sheet in hard with the main up without hitting anything. If your vang is adjusted to prevent this, then you won't be getting the proper sail shape.
Perhaps your dodger is too high or your sail is not cut properly.