You say "tons" of law and other legal documents would have to change in order to give CU/DP the legal protections being requested by same sex couples without listing any. This leads me to believe that perhaps it may not be as difficult as you assume since it appears you have not given it much thought.

How about a summary of 1,138 (eleven hundred thirty eight) rights/privileges as compiled by the US government's GAO (link).

I assure you, I've given it more thought than you think, and likely more than you have. I've had gay friends who were unable to make medical decisions for their partners (who had no other living biological family). I've seen their partners be denied access to spousal health care benefits. I've seen it all happen in real life, to real people that I know and can touch.

Brad