Champdogs used to be a fairly reliable way to find a reputable breeder, but sadly more and more irresponsible breeders are creeping in. All KC registration means is that the dog is KC registered and that should mean it's parentage can be verifiable, but KC registration is not a sign of quality. In fact, around 90% of KC registrations are from 'volume breeders' or puppy farmers to you and I.
It doesn't matter if you want a show dog or a pet dog, if you don't use a breeder that shows (or works) their dogs then you won't be using a reputable breeder, because if they aren't showing their dogs and therefore breeding to try and improve the breed, why are they breeding? Also, most people want a dog that looks like their chosen breed and you are most likely to get this with a breeder who breeds conscientiously. Of course, not all puppies from breeders who show are show quality, but they will be KC registered, they will be bred with the desired temperament and type of the breed in mind, they will be bred from health tested and healthy parents with good temperaments and reared with some level of experience. The breeder will also be experienced enough to offer you good 'after sales' advice and lifelong support, if you need it.
However, not every breeder who shows is reputable, but the breed club for your chosen breed will be able to point you in the right direction.
However, that said, as a breeder (not of Weims) I wouldn't home a puppy to someone who was out of the house for five hours a day. In fact, my preference is for someone to be available all day for the pup. Other breeders are more flexible on this, but please be aware that good breeders, like good rescues, are only interested in the welfare of their animals. It might mean you need to do some searching to find a good breeder who will accept you on their waiting list.