With minor side tracks into other current political issues
Look up the definition of Power of Attorney. I happen to know that it is up to the Hospital staff and know of one case close to home where my gay neighbor had this very problem and they allowed her to sleep in the same room with her partner.
There are some serious flaws in the PoA substitute for SSM, most notably the following:
"The person who creates a power of attorney, known as the grantor, can only do so when he/she has the requisite mental capacity. Suppose the grantor loses capacity to grant permission after the power of attorney has been created (for example, from Alzheimer's disease or a head injury in a car crash); then the power will probably no longer be effective"
While one can get what's called a "durable provisions" PoA, it is not exactly nationally recognized so you can end up with a document that's not valid "everywhere" and in some cases businesses that are not in a recognizing state. Which is also a problem here:
"Although a power of attorney grants the agent powers to perform acts in the absence of the grantor, the POA cannot grant powers to the agent that conflict with rules and regulations governing people and companies that the agent deals with. For example, if a bank has regulations that require the grantor to be physically present in the bank to perform certain actions, the POA cannot grant the agent power to perform those actions in the absence of the grantor."
Not to mention the bible-thumper hate groups have already made it pretty clear that they want to deny services to LGBT's, given that they could write in regulations that render POA invalid, it is not a solution.