Hi mtee.
As spam man says the practice for increased wind strength sailing above a certain degree is that you reduce the sail area which allows for forward motion without the vessel being laid flat on it side (Broaching)
The yacht racing boys have several suits of sails the smallest is called a "storm suit" which is what you require. The mast support lines
ie: (Shrouds - support wires for the mast) you can use use fishing trace wire (See link) crimp one end on to a hook the other on to a turn buckle, bottle screw, rigging screw, what ever its called in your area. Hook goes to mast top turn buckle to deck plate. Adjust turn buckle to put tension on the wire.
http://www.tacklebargains.co.uk/acatalog/Trace-Wire-and-Crimps-Kit--Coated-.html if you note the length of the keel on the modern racing yacht is quite substantial as the hulls have got narrower and faster the bulb weight goes further down into the water dont know if you can add a bit on you keel ?
cheers Frank.