I've done the locks by myself several times and have found it quite easy. It's a bit harder in the C-Dory than our Whaler since I have to run in and out of the cabin and don't have as good of deck access, but it is entirely doable. The biggest problem is people who lack any kind of boat handling skills; I've watched boats spinning in circles as they pinball through the crowds.
The only reason I'd be hesitant to go through by myself is you never know if you'll get put in the big lock or the small lock. If you are in the small lock, it's easy, since you just tie off to the floating wall and wait and you don't have to tend your lines. The big lock is normally easy too, since they typically raft small boats off the bigger boats. This January, though, I was put in the big lock, on the wall, and was really glad I had someone else with me. Quite frankly, I don't know if you can do the big lock, tied to the wall, in a C-Dory with just one person since the bow and stern lines must be constantly tended.
If you go through the locks, make sure you have fenders and lines on both sides since you don't know which side you'll tie up on, and you don't want to be scrambling to switch everything over at the last minute. If you have decent boat handling skills and you aren't on the wall in the big lock, you won't have any problems coming through alone. The guys working at the locks are clear, professional, and helpful. Follow their instructions and you'll be fine.