Jelly is such a sweety... love the seniors! Many here do use pee pads on decks due to apartment living, one member even has a fake grass area that they can clean and resuse. I am sure you can train her to use the pads. i will tag a few members that might be able to help with the idea.
as for quality of life, I have not yet experienced this, I have lost my boy but it was a sudden illness that took him in one day, but i will tag a few members that had to make this choice for one of thier beloved babies.
Good luck to you and hugs, prayers to sweet jelly!