The other alternative is to be really strict at controlling her inputs of water and wet food. If you only feed her once a day, and don't leave dry food out (shame on you if you feed a cat grain based food anyway) you can predict when she will need the toilet and make sure you double and triple check her trays to make sure at least one has no poop in it.

If it was a neutered male you wouldn't have this problem, so long as he never got nervous while young and wasn't neutered early enough, that he started spraying.

If you think female cats peeing on blankets is bad, you should see what it's like when boy cats are nervous, usually due to dogs, other male cats or people who torment them, their pee smells WAY worse than female pee.