Hey Scooby,
Don't take me so literal. If the halyard is not strong enough to induce normal mast bend, then use a substitute line. Borrow a dock line from a 60ft monohull if necessary. That should be large enough to do the job. Some boats like some A cats don't use halyards. They simply turn the boat over on the beach and tie the sail to the top of the mast.
The important thing is to bend the mast to a point at or near the max bend you ever sail with. Then measure the mast bend offsets every foot or so from the gooseneck to the top of the mast.
Take this data home and make a table. Plot the curve, mast deflection vs luff length, and make sure it is smooth; no bad measurements. Divide the max mast bend offset into the other offsets and express the mast bend data as a percentage of max mast bend. Give a copy of all of this work to your sailmaker and he will fix your sail.
Bill