Feed the larger snakes multiple prey items.
Example: You purchase a young BP just now starting to eat adult mice / rat crawlers. Buy a bulk bag of that size. When they start getting "too small" feed two items.
When you run out, upgrade to the next size and start over.
This is what I have been doing for my BPs and Kingsnakes with no problems. They don't get exponentially huge like you hear some people talk about, but they aren't small either.
I have a male '09 Pewter, 898 grams, I will be breeding this fall. I don't power feed, I was just lucky this guy never went off feed over the winter 
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Lincoln, NE
0.1 Pastel, 1.0 Pastel het Pied, 0.1 Pied, 0.1 Cinn, 1.0 Black Pewter, 1.0 Woma (hidden gene?), 0.1 Yellowbelly
2.0 Normals, 1.0 Thayeri, 0.1 Thayeri X Alterna, 0.1 crazy cat, 1.0 husband