Sounds tough. Is there a quiet activity he can do in bed when he's feeling a bit wakeful? You could say, you don't have to sleep, but you can rest on your bed while doing xx'. Riv has a wind-up torch that is pretty handy when I want to keep him in bed, he winds it up and shines it around the room. Would that work?

Shell, we don't have a tree for peeing! No garden at all yet! (so depressing!)