Hi Nick, I wish you all the luck with your kings, but brumation is not the key.
Its how most of these people think. Or appear to think(I cannot figure that out) You appear(i really do not know) to think your conditions are a constant and your trying everything but changing conditions. To me this is wrong.
I always manipulate cage conditions first. All these kings will do so so so much better if you provide an average cage temp in the sixties to mid seventies, then provide a hot area from 90F to 100F. If you do this and your animals are not dehydrated, they will not only eat pinkies, but will attempt to eat you too. Or any dang thing they get in their mouths.
I have been breeding cal kings since 1964 and after I learned to give them a choice, I never have problems with babies feeding.
Heck, a funny example of feeding quickly after hatching. A friend was hatching some L.greeri eggs(from nature) amoung the first in captivity and one slit then the another, then one reached over and ate the other. hahahahahahahahahahaha Well it was not all that funny at the time, but its only an example.
Snakes in nature cannot afford to miss meals, life if challanging. They feed quickly and as much as they can. And heres the key, "weather permitting". Sir, we provide the weather in captivity. Your weather is not permitting.
I guess I will add this paragraph to all my posts, you can take this information or leave it, but please do not attack me. Cheers