You can expedite the process by drafting a special document that allows all these rights to be conferred as part of a package deal, but now you're on the verge of reinventing marriage.

But if different groups (e.g. different churches or other kinds of organizations) hired lawyers to prepare different standardized packages, they would be able to offer different kinds of contracts that would correspond to that group's concept of marriage. That would give an individual more freedom to choose and would make it unnecessary to solve issues of non-traditional marriages at the political level, and I think that making things less political is usually a good thing.

Of course, there would be more legal paperwork, and, as you've mentioned, there are various risks related to that, in addition to other things.