You don't want to focus on hidden registrars but more like if you can appoint nominees legally! It will also depend on where you want to open a bank account. If you want to open an account in a real offshore jurisdiction they most often don't care where the company is registered as long they can verify the documents. For instant in Europe it is different, there I would focus on Gibraltar, Cyprus, Malta and Ireland, the latter︀ I don't know what is possible, still exploring my options.