moving the winches
I've had my C30 for 8 years, and most of my sailing has been single-handed. If you are simply out for a daysail in an area with little traffic, steering from in front of the binnacle and tacking the boat from there will be fine.
However, if you are interested in singlehanded racing, mounting a second set of winches farther aft or moving the original winches farther aft is, IMHO, the best path. Yes, a reliable autopilot is helpful (and allowed in most singlehanded competitions). But the autopilot's self-tacking feature requires that you set the angle of the turn you desire to make, then lock this into the unit's memory. You will not always want to make a 90 or 100 degree tack; the angle you want depends upon the point of sail you are on at the time. Besides, fumbling with the autopilot while you are attempting to handle the sheets and steer from forward of the binnacle is a hassle. I don't like doing it even when I'm not racing.
I purchased a second set of winches and mounted them farther aft. This is absolutely one of the very best upgrades I have made to the boat. In addition to use while singlehanding, they also can serve as spinnaker winches. Granted, this is a rather expensive upgrade.
Moving the original winches farther aft is a very good alternative option. In order for them to fit on the coaming, and for the winch handle to clear the stern pulpit, you will not be able to move them as far back as you might think. However, they will still be very easy to access from behind the wheel. Crew members would still have easy access to them.