Two rabbits are not more work & trouble. Two rabbits in separate cages are twice as much work, but if they are bonded & share a cage, only one cage, water container and litter box need your attention.
That isn't much extra work at all!
Please, only put rabbits together if they have been spayed/neutered.
Does your bun dig up the hay and litter in his litterbox? Try this: cut a piece of wire mesh from an old cage (or buy some mesh at the hardware store). A 1-inch square mesh works fine. Put down a layer of litter in the litterbox and place the wire mesh on top of it. Then add the hay. Mr. Bun can dig the hay, but he won't disturb the litter. (This works great with the wood pellets described above.)