Plan on a remote camping trip in mid to late January. Are there designated sites and are there pit toilets? Any recommendations appreciated.

Sites yes, and a port a john

I stayed at the Bridle Campground. No water in the Winter, but they do have a pit toilets at the campground and at the parking lot for the Rhodadendran Trail open year round.

I was there "off-season" recently and it was pretty nice. Access to heated bathroom 24/7 with running water at the contact station. That being said, unless you are in Backcountry, I believe that they said no camping passes dec-january because it's so cold.

I did see facilities with toilets. Not sure about designated camping sites. It will be extremely cold in January!!!