I'd be more inclined to sort out the
rigging issues with the current
rig. A well designed gaff rigged sail of that size should be a piece of cake to handle. See if you can find a Doughdish or 12-1/2 to look at, I had one and the gaff sail was very easy to handle.
Hard to tell from the pic but are there two halyards or just one? I know there are some gaff rigged boats with single halyards but with two (peak and throat) it is very simple to get the sail shape right. The yoke on the gaff looks very short, extending the
horns out in front of the mast should help keep it in place. Also, the sail doesn't look like it fits very well, the throat cringle isn't anywhere near the gaff as it should be, and the head and foot of the sail look to be almost as long as the gaff and boom, limiting your ability to get any proper tension. Not sure who made the sail but most sailmakers these days do not know how to properly make a gaff sail.