Seriously, you never see them working because it's night time, and even if you stay up all night, it just gets done at 6 AM, between one blink and the next, like magic. And none of the other villagers complain about the noise. How does he pull that off? Does he have magical elves or something?
I love the hammering sounds when a new shop is being built. I can just picture all the contractor village types happily working away inside. You know... I think it's high time we had another AC movie! I remember a cartoony one came out a while back.
I'd like to think he has like cousins/family members who owe him that help him. (Or maybe they're just a tight family? He doesn't seem like the type but... who knows.)
I think all the construction in the town is done by gyroids similar to Lloyd. Not sure how they would climb ladders or something but I'm sure they find a way.
Personally, I think it's a one man job. I don't think he'd employ any helpers or anything. He's waaaaay too cheap to want to pay anybody for their services, when he's making a living for himself too. I think if anything, he'd probably force his nephews into being his renovation crew, because they're family and chances are because they're so naive they'll do it for free. Kinda like how it seems like he forced them into the family business by having them work for him on the second floor of nookingtons.
He's probably been using Wisp as slave labour all these years. And Wisp could be moving every villager in and out at 6am, not just the ones done via amiibo cards and figures.