It is real easy to get into trouble in cold weather or cold water.
Pick your water carefully, keep a close eye on the weather, maintain a bail-out bag with you in the boat, learn how to use the contents of the bail-out bag, learn to use your boat well, dress to stay dry if you fall into the water, dress for the water temps and not the air temps, and above all use your head.
The bail-out bag should contain fire making materials, high calorie food (like a protein bar and granola bars), a spare set of dry clothes, a "space" blanket, and maybe a small shelter of some kind (like one of the space blanket bivies). I also like to take some hot tea or hot chocolate in a thermos when the weather is cold.
As far as whether you are crazy to go alone, it all depends on your skill level and the other choices you make. I will say that it is very easy to get into big trouble fast, especially when alone. I lost a friend who was paddling in waters familiar to him a few years ago. He was very experienced and well equipped. The weather turned unexpectedly and instead of small waves in a protected cove, he found himself in big trouble.
On the other hand, my step-mother used to do everything wrong when she paddled and survived things without even much of a scare that would have killed stronger, younger people.
Full Size Sail Rig
PFD's (Life Jackets)
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