Hidden Fully Upgraded Castle idea

[Virux]

Would it be beneficial at all to have some Free Castles scattered through out the map that are fully upgraded yet you only see "40" on their size? The full upgrade only triggers once its captured. Think that could increase captures of Free Castles at all? Personally I only take them when starting out but it could be a great way to increase the capture for filling in Strongholds and the like.