I have that incubator and my serama turned and hatched perfectly fine in it.I think I’ve done some in it, I honestly can’t remember
I know I did bantam cochins in it just fine.
I think they would be ok though, they would just maybe stay against one side of the turner slot, and you may need to check them every so often to make sure they are positioned ok. Or could you hand-turn? You could just take the turner out, if you are able to hand-turn. I wish they made another turner rack with smaller slots.