I have tried the medium sized one on my chihuahua and he is about the same size. I feel that they would work for your dogs. Yes I do make these, my mom and I had made them for a groomer. When I had used these vests for my dogs I was able to pick them up just by pulling up the leash. So I would say that they are pretty secure. They are held together with Velcro.
I have a little bit bigger size that would work. If you win I have one similar to this but I had made quite a few so I'm not quite sure how many different patterns I do have.