If you source from a dedicated breeder who records all the traits and culls heavily on failure for desirable traits then you will get low maintenance sheep
That would be quite hard, i guess you need good contacts
So what are the problem traits?
Lambing problems? I cull anything that needs assistance and it's offspring
Mis mothering? As above
Feet problems? Anything ever needs treating/trimming gets culled
Worms? HIgh FEC BEV animals get culled too
Etc etc---there are people who do it.
It is hard the first few years but after that most problems have dissapeared
But minimal does not = no maintenance