I'm by no means a pro here so take it for what its worth...
Are you only wanting a portrait crop? With the white back ground, you could add to your canvas to each side allowing you to still crop at the waist but you would be able to show the models arms without cutting them off. You would then have the same shot as the b/w in number 2, which I also like between the two, but it would be a landscape image rather than portrait.
Not sure if that made sense, just my $0.03
Even a blind squirrel finds a nut now and then..... me