Um, yeah....about that "sage advice"..... I ain't got none. When Scout was hatched, he and his mom were in a wire dog crate in the coop in full view of the other adults at all times. After a couple of days I opened the door of the crate and she took him out among the other chickens, and boy, was she protective! After he got hurt and we brought him into the house, we used Mama Heating Pad and the same crate he'd been in outside. His hospital room was in the living room. I don't think he ever really got lonely - he was handled a lot for his treatments and then tucked back in. He was always pretty content, but on those rare occasions when he'd start that insistent peeping we'd check to see if he was alright, then leave him to figure it out. At night when the lights went off, he went to sleep and slept all through the night. That one little factor, I firmly believe, is the difference between a calm chick and one that seems to frantically need reassurance at all times. A chick under a light has no idea of day/night cycles. If a chick is in light 24/7 and can make demands anytime he feels a little insecure, that's just what he's going to do. Mama Heating Pad gave him what I couldn't - the feeling of a broody hen's warmth and security. It's more than the heat - it's a dark, quiet place where he's surrounded by comfort, and it feels like he's not alone because he's out of the huge big world. He learns to calm himself.When Gus was in the pen with the big girls, what was his demeanor? Was he content? Or did he still chirp his head off? I'm betting he enjoyed his little outing, and he's hoping you'll figure a way to make it so he can be out there with them, if only during the day. Did you read about Blooie's boy chick Scout? She may have some good tips on how to keep Gus from being lonely at night. Maybe I'll ask her if she has time to come over here and give us some of her sage advice.
As soon as he was stronger, he went right back out with the other chickens - at first he had supervised visits and his mom did a great job of stepping right back into her role as protector. When he went back outside to live for good, we used that trusty crate with the door wired enough so that he could get in but they couldn't follow. He got pecked a bit, and he learned where to hide or when to peck them right back. Now he's a majestic, protective roo. He's not a snuggler - despite all of the handling as a chick he's independent and he doesn't run up for attention. He also has some kind of inborn confidence that tells him his place is secure and he doesn't see anyone going out to the coop, the run, or the yard when they're free ranging as a threat to his position so he just moves away.
So I have absolutely no clue how to advise here. My chicks are all raised outside with the others, (aside from those couple of weeks with Scout) and have that heating pad to run under if they get spooked or feel alone. Well, there ya have it....some not so sage advice. I decided last year that I wasn't going to be a "chicken mama" anymore. I can't do it as well as a real mom but I can provide the them with something that takes her place.