I gave him one this morning, he chewed till he fell asleep, not sure whether to give him one at bedtime though
Yes, give him one at bedtime too. It doesn’t need to be stuffed full. Whenever I go out mine have a Kong just smeared inside with a little bit of peanut butter - and when they go to bed in their crates at night too. They have frozen Kongs if I’m going to be out a bit longer. I think they probably finish them in five minutes or so, but it fills their tummies and eases my conscience!
It’s all part of their routine now. If I’m getting ready to go out, Tuppence is clever enough to know whether she needs to go to wait by her collar to come for a walk, or by the sink for a peanut butter Kong, or by the freezer for a frozen one! If it’s Kong time they rush into their crates ready to be given them! They’re not shut in their crates during the day now, but they still use them as a ‘den’.
Are you using a cue word for him to pee and poo? Try that (I use ‘be quick!’, but you can choose your own) and don’t interact with him at all other than that during the night. He’ll hopefully get the message that night-time isn’t much fun!