Hey Minky!
Just a thought....I noticed recently that Inca (biting diminishing nicely thanks
) has been a bit less keen to get in her bed at bedtime lately, and I wondered if she was cold. Think-moments before curled up next to me or the woodburner..so( yes you can all howl with laughter now)..I have started tucking her in. In can't believe I said that out loud.Hahaha Anyhow- she loves it!! Bed time is 10pm, milky bone, Gets in her bed with furry toys to keep out draughts and I tuck her little fleece blanket over her and she snuggles right down and straight to the land of nod. We have a blanket in the winter don't we? He may be waking up because he's a bit chilly- then once you're awake you need the loo. You could check that first.?
My pooch has a bed and an area in front of it about 3ft square with water bowl and a few toys that are safe to leave. A couple of weeks ago she had a funny tummy after a wormer and did make a little whine in the night. When I came down in the morning there was a poo. We said nothing, greeted her as normal and just cleared it up. I don't think it affected the housetraining. At the end of the day, they don't want to mess indoors so that behaviour shouldn't stick and an accident is an accident. Where, your dog thinking that it's ok to get you up in the night might stick as it is something he would probably quite like? I am no expert but just some thoughts I had.
Perhaps if you gave him the latest poss loo trip before bed then make him really cosy, with access to an area that isn't his bed just in case of emergency and leave him ? Might be worth a try