I like making it harder to TO a region. Either make the progress of TO a very long one when your density is too low or increase the number of men required by a lot might do it. Making TO long as in will require like months to TO one region unless you have enough men. As for selecting which region to give up, once a realm falls below a certain level, they should definitely get a warning message first. Once it falls below the threshold, then the ruler should be given an option to let a region go rogue.
