Indeed it would be the simplest solution just to allow klan raiders to have ~ 40-50 bonus Log in to see images! itself and not how you can earn it… though this might make klan raiding less challenging, so maybe restricting the available visits is indeed a better solution. However, I wonder if it was necessary to restrict the contributor characters per player to one if you already restricted the overall amount of contributor characters.

By the way, you might want to consider to influence klan raiding in a way that it becomes more challenging than it is atm. For example, introducing a harsh time limit (e.g. 30 minutes/day) could make sure that klan raiding still remains attractive for competitive players without making it too exhausting.

Yes, those solutions are not really good-looking and far from perfect, but at least they would work.