And a fantail wouldn't need a larger area than that? I could easily do a tractor with a 4x4 indoor area and an area as big if not a little bigger to give them somewhere to take baths and flap around.If he can't fly he probably doesn't need a large aviary, but needs some room to flap around, and he without a doubt needs natural sunlight daily. I'd say him and 1-3 other pigeons could comfortably share a 4'x4' loft with a 2'x2'x2' aviary.
If you want to get a pal for him and don't want another flying breed, consider an ornamental non-flying breed like a fantail. They are known to be docile and friendly.
Felix is fluttering a little bit, I caught him fluttering in his cage up onto something that's about 4 inches off the ground, that's about the extent of his flying through.
(Our houses were very close together). I had his loft on my deck so I could see him from the living room window. After the complaint I moved him to the only other spot in the yard where I could still keep an eye on him from another window, but it was only about six feet away from the original location. There's now a shed between the loft & the neighbor, which I guess blocks the noise. When I asked the neighbor about the noise again they said they thought I had gotten rid of him! Good thing, because in the meantime I had gotten another pigeon who turned out to be a female, and they had babies!
So now I have 2 males & 3 females. [I did have one other male baby but I gave him away because he was fighting with his dad. The other male baby is peaceful.] I can hear my male pigeons very softly at night when I'm awake in bed because the loft is now close to my bedroom window, but I kind of like it because it alerts me when people are walking around outside my fence. That's the only time they make noise at night. They're great "watch dogs!" It's not loud enough to bother me at all, and certainly not loud enough to wake me. In your case, I assume they only complain about the noise when they're in the loft, not flying around? Any physical barrier should help a little (a shed, evergreen bushes, solid fence, etc.) The males are more noisy, so if there's any you would be willing to part with, that could help.