Winter storms
I agree with the previous comments regarding the relative ease of going North in December. If you have a ham rig, or at least an HF receiver (you can get a portable for about $200, but be SURE it can receive SSB) you will be able to listen to the weather forecasts on the various nets. There are a relatively few places to hide out in the event of storms, but if you pay attention you should be fine. For the time of year you are considering, San Carlos has the disadvantage that you have to get there. And why might that be tough? Well, it is the season for Northers in the Sea of Cortez, and it is very hard to make progress against them. They come through quite regularly at that time and you have about 400 NM between Cabo and San Carlos. So, instead of simply enjoying whatever part of the Sea that the weather gods allow you, you might be pressuring yourself to go when it is uncomfortable. Plus, you might enjoy spending a little time in the Mazatlan / Banderas Bay area before heading north on the "outside". One other thing to take into account, though, is that getting from SD to the Bay area can also have its challenges during the winter. However, if your schedule gets tight, I suppose you could always leave your boat somewhere along the way and continue the delivery later. I agree with the comments regarding the competence of the crew at Marina San Carlos, and I doubt that there will be much of a crowd waiting to truck north in December.