That's awesome! I never used feed hoppers either, they weren't built into the racks I got, and I never installed any. Usually the food went on top of the rack wire, and if I used smaller food, it fell through and was in the substrate, and the rats did just fine.
I realized I was overfeeding the adults too! They wasted tons of food, hiding it everywhere and never eating it, since I'd put MORE food in when the stuff disappeared.
Thanks for posting.