A good number of swing keel owners keep their boats slipped year round. Maintenance depends on the material the keel is made from and what it is protected with.
I've not looked at the Cal 22 swing keel up close so I'm not sure if the keel is lead or cast iron. The Cal 22 is essentially a knock off of the Catalina 22, so I am assuming it is the later. Catalina did not start producing fiberglass sheathed lead keels until 1996 I believe, so pretty much all of us C22 owners deal with the maintenance issues of cast iron.
If you have lead, you have few worries... For cast iron, you need a good epoxy barrier coat under the anti-foul paint. If you look in the C22 forum you will see that a number of us have gone through the extensive project of removing the keel, sand blasting, and then repair/fairing with epoxy, barrier coat, and bottom paint. Once that is done all that is required is typical bottom paint cleaning and recoating every 2 or 3 years (which is way easier and cheaper if you can haul out on your own trailer).