Hi, regarding XRefs, there is not difference between Forest Lite and Pro.
In both plugins, Camera Limit should work fine if the Forest Object is stored in a XRef scene, or imported as a XRef Object.
Just turn on Camera->Assign to Active view. This is specially necessary when Forest in a XRef scene, because there is no way to modify the "Camera" parameter manually.
Alternatively, you can keep all Forest object in the main scene, and move only the geometry (Custom Objects) to XRefs.
In this way the scene is lightweigth, and it's easier to modify the Forests. There is not any performance hit using this approach.