Have you considered hooking into item:saving Sitecore event? You can retrieve an item being saved and sanitize its fields:
public void OnItemSaving(object sender, System.EventArgs args)
{
Item item = Event.ExtractParameter(args, 0) as Item;
Error.AssertNotNull(item, "No item in parameters");
//modify item fields as required
}
public void OnItemSaving(object sender, System.EventArgs args)
{
Item item = Event.ExtractParameter(args, 0) as Item;
Error.AssertNotNull(item, "No item in parameters");
//modify item fields as required
}
More info in John West's post: https://community.sitecore.net/technical_blogs/b/sitecorejohn_blog/posts/repost-intercepting-item-updates-with-sitecore
