@Stephane Aloise Can it be done? Yes. Not sure what needs to be fixed on the spreader.
Should it be done? That is a question only you can answer. Your boat your decision.
What are the risks? First your sending someone up the mast to remove the supports that maintain the mast in column. In perfect windless weather and calm water, you may get away with it. But a 200 pound person near the top of the mast will be putting considerable pressure on the mast. Your going to be removing the stay's so you can get to the spreader. What can go wrong with this action. I would guess you'll try to replace the stay with a halyard. The wire has no stretch. Most halyards on boats have stretch so the halyard will give a little when under pressure.
In an emergency could this be attempted... Well yes depending on the emergency. If I had plenty of time and wanted to do the job correctly with very low risk... I would remove the mast from the boat do what ever work is needed then reinstall the mast and sail knowing I had protected the boat and any worker involved.
Keep us informed of your choice and how it worked out.
