Since the reservation is in your spouses name, why not add your name and your platinum # to the reservation. I do this all the time when Mrs. OU812 has a conference and I am tagging along. Very ofter this will result in an upgrade before arrival. You can always bring your platinum card with you to show when checking in just in case.

Also, with regards to the Gold/Platinum challenge, I believe the bestow they status upon you immediately and take it away if you don't complete the challenge.

Regards,

RIP...