Dog toileting inside consistently

I’m in desperate need of some help regarding inside toileting from my 9 year old Chihuahua yorkie male dog.

He consistently toilets inside during the night. And occasionally during the day. He’s quite an anxious dog, he paces at night and has a few signs of cognitive dysfunction.

I’ve tried reducing his water intake at night by only leaving a small amount in his bowl.

I’ve also tried walking them just before i go up to bed, to get anything out of him, but he still toilets inside.

It tend to be up the washing airer, but if it’s not there it’s usually up the sofa. I’m worried that if I remove the airier he’ll just wee up the sofa instead, which is an absolute nightmare to clean as it just gets everywhere, atleast with the airer it’s just in a puddle on the floor.

He eats 4-5 hours before bed and does go out to the toilet.

What can I try? Should I try a calming medicine? A dog litter tray?

I don’t want to limit his space during the night as I know most people recommend that as they don’t like toileting in their own space, th sofa is in his own space so this clearly isn’t too big of a factor. His anxiousness is also why we don’t do this as he’ll just cry or scratch at the door. I also don’t think it’s fair to trap him in his crate overnight.