How Do I deal with my dog's steroid related bladder control issues?

My 9 yr old boxer was recently diagnosed with cancer. She had a surgery to remove a tumor on her ear which was causing her discomfort (She would scratch it until it bled), and we did a biopsy of another tumor on her shoulder.

After a lot of soul searching, we’ve decided not to put her through chemotherapy and radiation for this disease.

My vet recommended we try steroids which have significantly reduced the size of the tumor in her shoulder and have made some other bumps which I suspected to be other tumors disappear.

The steroids have made her excessively thirsty though which isn’t too hard to deal with during the day, but she has had some overnight “accidents” where she did not wake up to ask to be let out.

This morning was heartbreaking as she tried to “clean up” the mess she made on my bed this morning when she woke up and realized what she had done.

My vet is out of the office until January 4th and I do not especially want to talk to her partner (who turned out to be very cruel and second guess her recommendations when I did try him recently on another issue)

Has anyone dealt with this problem before? She has never had any bladder control issues before, but she is an older dog.

Is there such a thing as doggie diapers?