Also note that you're going to get the contents of the subsidiary hashes flattened out into a list of key value pairs when you do { %params, %extended_params, ... } like that with whatever appears for any given key last winning (e.g. if %params and %navigator both had a key "foo" then the new hashref's value for "foo" would be what was in $navigator{"foo"}).

(Which may be just what you want, but just calling attention to it.)