I agree, leave her in the laundry room, if you feel you would like her to have some company, why not put up a baby gate so she can see the other dog, but still has her own space which it looks like she prefers to keep clean.
Not all dogs are the same, someone I know has a small terrier which was 18 months old and still peeing all over the house. Although I feel their methods of training left a lot to be desired as they were using the old trick of rubbing her nose in it which I found disgusting.
I am also now dubious of them not soiling their bedding area since I tried crate training my new puppy, as he peed in the cage, so I just left him with the run of the kitchen and within a week he was clean day and night, and has not been a problem since. My eldest bitch never did anything in the house from 8 weeks old, yet my younger one took 3 or 4 weeks.
Make sure she goes out last thing at night and feed her last meal at tea time ish so it has plenty of time to go through before bed time.