As far as the non-skeg rudders are concerned, wander around a boatyard and look at boats that are hauled out. In many cases the rudder and its post are holding the skeg on. If you shake a few you'll see where the strength comes from. If I was having a boat designed today it would be a spade rudder without a skeg. Built with suitable strength of course.
As far as the older Spencers, yes they are older but if well kept and upgraded that isn't always a problem.
I agree with the bowsprit comments as there are also anchoring issues to deal with and it's a lousy place to be when it's rough.
Living aboard in Victoria Harbour