[sailingdog]

Sounds like both you and your wife need to take some courses on sailing, that teach the basics of sailing theory and science.

That said, few boats will sail safely under just a 135% Genoa, particularly upwind. Using this sail will often put the center of effort (COE) forward of the center of lateral resistance (CLR—usually near the keel's center). This makes it very difficult to tack the boat through the wind, with out the help of the main sail to balance the boat. This will also generally leave the boat with serious lee helm, which makes the boat difficult to sail upwind, and is fairly dangerous—if you lose control of the boat, it will head down, and if you're sailing close-hauled and not able to release the sheets in time, will come through a beam reach and seriously risk getting knocked down. A slight amount of weather helm is preferable to any amount of lee helm.

Some boats do sail well under just the main alone, but in many cases, this puts the COE behind the CLR, and may cause serious weather helm... making the boat harder to keep under control.

Ideally, the boat should be almost balanced with the COE almost directly above the CLR. As a boat heels, the COE moves outboard, and the hull's water profile becomes asymetrical, which both will tend to cause the boat to head down, if you're sailing upwind. Under just the Genoa, this is amplified.

If your wife is insistent on sailing on just a single sail at a time, which I don't recommend, I would say that you will probably want to sail upwind on just the main and downwind on just the genoa. At least doing this will put the COE in the proper location with respect to the CLR and help keep the boat going in the direction you want.

If your wife is so concerned with minimizing heeling (not healing, which is what you need when you get thrown across the boat and hurt) and believes that the only way to sail a boat is to sail it level, you would have been much better off getting a trimaran or catamaran.