I have done quite a bit of single-handing over the years. A lot has changed in the years since I single-handed my Folkboat back in the 1970''s to single-handing my 38 footer today.
Folkboats make great single-handers. They are long keeled 25 footers that track well and yet still offer reasonable maneuverability. Their fractional
rigs have smaller
jibs which are easier to tack than those on a masthead
rig boat. They have an outboard rudder which is pretty easy to adapt to a wind vane by adding a counterbalanced trim tab on the trailing edge that can act as a servo to turn the steering rudder.
If you chose to go traditional, which it sounds like you are inclined to do if you are seeking a full keeled boat, then I would try to find a used copy of either Ian Nicholson''s book or Richard Henderson''s book on single-handing. Both are a little dated but I have not encountered a good, more up to date book on the subject single-handing. I would also suggest that you try to find a copy of Richard Baum''s book ''By the Wind'' which is about a fellow who did a lot of single-handing in a 35 foot engineless cutter after the second world war. It gives a lot of good ideas about single-handing simply.
As I said a lot has even in the 15 years since these books were written. Low friction blocks allow
lines to be more easily lead back to the cockpit. High quality sheet stoppers have made slab reefing easier to use and reduced the number of
winches required to operate a boat. Fin keels and spade rudders have reduced the load on the helm making longer steering times less tiring and require less draw from a
autopilot or less strength from a windvane.
Autopilots are less expensive to buy than a well made windvane and are more useful in a wider range of conditions. On small boats it is helpful to be able to do as much as you can without getting too far from the tiller or tiller extension.
Otherwise, single-handing is mostly about developing a sequence for doing things, thinking well ahead of yourself and asking a lot of ''what ifs'' and having as many answers as you can thought through and lastly it is about developing a sense of timing for how quickly things happen on the boat and when each step of a task needs to be done. The good news about that is the best way to develop that skill is simply to go out there and sail.
Good luck,
Jeff