I think that a third wheel design would be useful for crosswinds, but what happens if the wind is coming from the side that the third wheel / outrigger is on ?
The bike would still tip over on the unsupported side.
Has anyone noticed that many of these faired in motorcycle designs don't seem to be too concerned about crosswind stability ? If you look at many of the designs from the front, they are wider than they need to be . The designs are very rounded versus slab sided.
Perhaps it is better to sacrifice a little CdA for safety.
Edit : When viewed from the rear, the bike does indeed seem to be very slab sided :
