Don't restrict his food to lessen his poops! Bunnies poop a lot, it's just their nature. Once he's older and neutered, he'll be easier to litterbox train, but their digestive systems are set up to be working all the time.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry