Help – Dog Peeing inside but only at specific time

So its a bit of a funky situation I just was hoping for some opinions and insight for, and if anyone has any, some tips/tricks that i can do to try and reduce this behaviour

He is a 2 year old Hairless Chinese Crested, that I would say is 80-90% toilet trained. I have heard from many other crestie owners that the breed has a nasty toileting issue, including marking, and while he does still mark the house on occasion, i can tell these are not his marking pee's.

Some extra details and notes about the house and his behaviours:

• He has 24/7 access to the backyard
• I have also bought in indoor turf container for him, with real grass turf that i have put in the room he pees in, in hopes he will use that instead (also for cold weather months.) So far he hasn't taken to it other then pooping.
• During the day, he goes outside on his own to toilet, no issues at all
• During the night is when he will go and he has one specific room in the house he constantly pee's. Also because we have been unable to catch him doing it and re-direct him, I am aware he likely thinks this is an ok behaviour to do.
• I have done my best to get him to go to the toilet before bed, in the turf mat or outside, whichever he chooses at that moment. He doesn't always go (i wait about 10 minutes) but even if he does pee/poop before bed, more often then not when I wake up in the morning there will be pee in the room
• He does have 24/7 water access, however i am reluctant to do the method of pulling it up for the night as I am not a reliable morning waker, and dont want him to go without for too long because i couldn't get up in the morning (especially during hot weather)
• I did also try to crate train him the moment we got him as a puppy, but (as expected of his breed) he has major seperation anxiety (which is also why we elected on a doggy door installation instead) so at this time, crate training for his accidents is not an option

He is healthy, no medical issues that would cause incontinence, so I can only assume maybe he doesnt like how dark it is outdoors, but since he has an indoor option, im at a loss for what to do going forward. I think he goes between 4-8am when everyones still asleep. He was pretty decent with his toileting until the last couple months he's been peeing inside almost every night.

I know this is a long post, sorry about that but thank you for reading through it and i appreciate any tips