For example since corporations (etc.) have no interests, if their behavior impinges on the interests of even one person that behavior has to be stopped, unless someone can show that that more peoples' interests are served by that behavior than are harmed.

In the case of TPP the attempts to show how it benefits individuals rely on a lot of hypotheticals which doesn't wash if we take this stance. Everyone gains standing to stop corporations if their interests are affected, and the burden of proof is on those who want to permit some corporate behavior that anyone opposes.

The fictitious person legal construct has legal rights and institutional interests. I'm not sure how that maps to social rights and interests.

In any events, rights seem orthogonal to morality. At least if morality constrains some portion of the acts that a moral agent could do because a right is a license for a particular course of action.

Anyway, while changing the laws might produce the greatest benefit and utilitarianism might be a good basis for rational moral action, that's not really my immediate intent. My goal is more pragmatic discussion and less sloganeering.