Hey there!
My thoughts are this:
That is great that you are concerned with overfeeding them, as that is a practice that does bring results that can be unhealthy and sometimes fatal. Just as obesity can hurt humans, it also can hurt your snakes.
One question: When you say small rats, what exactly are the size of the rats? An 04 pine will in no way be able to eat a small rat, as in 50 grams in weight, but possibly would be able to eat a pinky rat, like 3 to 5 or 6 grams.
Most of my pines will get one meal every 7 days or so. My biggest pine ( 6 foot ) gets a meal every 10 or 14 days, as does my biggest bullsnake and gophers. Their weight maintains very well. The meals are enough to leave a bulge, but not much bigger than the biggest part of their girth on their body.
Once a week works out great, but if you take a look and the snake seems to be a tad heavier than normal, skip that meal and wait till next time. It will not hurt them and they will still grow. In the wild, they are not able to have access to weekly diets like our captive bred pets do. They take any meal they can, and that can be every 2 or 3 weeks. Even with that schedule, they will still grow.
It is very easy to be eager to get our pines into breeding size as soon as possible, but then we always should keep in our minds the question," What is best for our snake?"
My baby Ocean Co. northerns I picked up in Daytona in August have grown appr. 6 - 8 inches since then with once a week feedings. My male adult Burlington Co. northern grew 5 feet in 3 years with once a week feedings, and that was sometimes me skipping his meals as well. His mother lived to be 24 years old, being born in 1979, and bred till she was 22 or 23. The secret? No power or speed feeding and keeping the weight in mind as she was fed all her life.
Hope this helps! Good post!
Billy

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Genesis 1:1