The hard part will be carrying the forces of the staysail stay OUT TO THE HULL. Just putting a backing plate in may not be a good idea. You may just succeed in lifting the deck off the hull.
And you may need to look at running backstays.
The PS deck is thru-bolted every 4 inches, and the plate should be pretty close to the bow (~12") where there is plenty of support, assuming its same configuration as the 31.