I wouldn't recommend a BTA and a Rit in the same small tank. I would probably not put the Rock Nem in with it either, but you might get away with it in a wider tank. I would honestly say you can probably get away with something like a 40 cube or a 40 breeder with some corals. For reference I have one in a 28 cube with 2 clowns and some Zoas, but I wouldn't recommend it with a tank that is not specifically for the Nem. Whatever you do though if you put it in a small tank, do not feed it as I feel the bio load they create is too large. You really have to place powerheads smartly and ensure you set him on a rock he's not likely to move from and can not touch anything around him. Goes without saying, but you'll need adequate lighting to keep him happy.
Make sure you run carbon.