Rabbits are very easy to littertrain. Typically if you leave the floor bare and provide a litterbox in the corner that they're used to going in, most will adapt quite easily. Spaying and neutering is also essential to litter training (as well as providing a lot of health benefits).
Hay makes very poor bedding because it is not very absorbent.
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