For an eight hour overnight, they should be 7 months old before being able to hold things in that long. Otherwise, yes, you will have to get up in the middle of the night.
Wow, I'm not sure I buy this. I've been fostering Kobe since he was 12 weeks (if not a bit younger) and he has slept through the night every night with no accidents in his crate. He usually goes to bed at 10 and is up between 6 and 7:30. Obviously, not all puppies are going to be able to do this that young, but 7 months is pushing it. During the day, I do go by the "don't crate for more hours than the puppy is months old" (ie 4 months = 4 hr max), but I don't do that with overnights. To be completely honest, I don't wake up in the middle of the night to let my foster pups out. Their new owners can do that if they'd like, but in the meantime, I provide a space big enough that they can potty in one corner and sleep in another if necessary. I know it's not ideal, but I figure that at least the pup is alive and out of the shelter where they would've been euth'd.
If I recall correctly, all of the other foster pups have also gotten to the point where they'd sleep through the night with no potty accidents either (none was older than 18 weeks before adoption.)
With regard to your question: Does the puppy avoid pottying in the crate? If so, I'd start by only letting him out twice a night for a little while, then bumping it back to once and then after a week or so of that, bumping it back to not at all during a very short night (say bed at 12 and up at 5 or 6). Eventually he should sleep through a regular length night. I imagine that he'll cry at first, but if my suspicions are correct, some of his crying is likely due to the fact that he has woken up in his crate alone and wants the comfort of a person. You let him out and likely give him a scratch or two before he goes potty. Thus, even if he doesn't actually need to potty, he might cry just out of a bit of separation anxiety.
I can't give any professional advice because I am not a professional, but if I were in your shoes here is what I would do. I would provide the pup with a crate just big enough for him and get him accustomed to it during the day. All meals in the crate and lots and lots of little snacks throughout the day in the crate as well. Anytime he goes in on his own, lots of snacks and praise. Make it a nice place. At night, I'd put him to bed with little fuss. Since he isn't used to sleeping very long without using the bathroom, I'd refrain from giving him snacks or drinks at bedtime except for maybe a bit of peanut butter smeared all over a bone or kong toy to keep him occupied. I'd make my schedule for how many times I'm going to take him out and stick to it. When he goes out, he gets no interaction whatsoever. I'd put a breakaway collar (or harness on him) overnight and simply snap the leash on and take him out on leash with no talking, no petting, nothing. Once he's done his business, he would go right back into the crate. I'd unclip his leash and go back to bed without making a big deal. If I was really intent on rewarding all outside pottying, I'd bring a few small treats to feed as he was pottying outside, but still refrain from much excess praise and excitement. After that, I'd ignore the crying until the next trip outside.
It might even be possible to sensitize him to your alarm by setting your alarm for a little before he normally cries to go out. Then let him out and eventually he'll learn that alarm = go outside. Then you could move the alarm sound a little bit and a little bit later until he is sleeping for longer durations. Just an idea.
You know your puppy better than I do, but I definitely think that with some hard work (and possibly a little bit of heartbreak as you have to listen to him cry without being able to comfort him), you'll be able to have him sleeping through a short night in no time. If he
does have an accident after he cries, you'll know that his crying really
is due to having to potty and you'll be able to take even smaller baby steps towards the goal.
