Try putting his bed in a cardboard box 📦. You put the box on its side so he has a ‘roof and walls’. They like to feel secure.
If you find that he’s peeing on his bed, then put it in a thick plastic bin bag, place in a pillow case and cover with a throw. It means you’re not constantly washing the bed, just the covers. Though you have to wipe the plastic.
If he still pees on your sofa, you can cover it with puppy pads and then put a washable throw over it.
You don’t need to use expensive sprays, just wash your floors with non bio washing powder, as it neutralises urine. Don’t use strong scented cleaners as that may actually encourage him to mark those areas.
Contrary to what people think, cats can not see in complete darkness, so if you are closing him in the bathroom at night, is it pitch black?
Enjoy. I only gave four cats now and they’re all in their (human years) late 80s.