Another idea: you could try moving the V3 vertices along their normals, to the point were the normal intersects the V1 mesh.
Not easy, I admit. The math to calculate the correct polygon to intersect is out there, but it's not as simple as I'd like it to be. And it'll probably be even slower than the matching vertices approach. But it will result in a far less ragged morph target.

The pen is mightier than the sword. But if you literally want to have some impact, use a typewriter

My gallery   My freestuff