Really nice work! How did you do your carving and shaping, especially of those hinges?
I found that, the longer the first section is, the more stable it becomes, and the harder the other two sections move. I can't get the head completely still, but I come close enough to get bit.
I use a 2/1/1 ratio on my three piece swimbaits, and keep the ballast in the head as much as possible. Back toward the joint in the head, moving forward until I run out of room, and then in the front part of the second section if needed.
I never put any in the tail. I find that, by keeping the weight in the front as much as possible and never in the tail, the bait swims level, since the PVC I use is buoyant.
Also, since I use screw eye and pin hinges, I adjust the joints so the first joint isn't too loose, but the tail flops side to side.
My three piece baits flap line a flag on a fast retrieve. I think that's the nature of three piece baits. A four piece bait swims in an S shape, like a snake.