I use plastic cat litter boxes and wash them with bathroom cleaner once a month (Lysol bathroom cleaner). I've had mine for years and they don't retain smell because they are sanitizedYou’re lucky your cat will use a stainless steel litter box. Cats don’t like the feel of metal when scratching the litter.
I buy cheap plastic storage bins from Wally World. They usually go several months before they start stinking of urine. When they do, I toss it in the trash and put out a new one.