For a time-boxed effort, I believe 256 is better than 128 (RFC-1035 defines the limit in terms of wire-encoding of the DNS message rather than the user-visible values (section 3.1, "To simplify implementations") - there's also a 63 byte limit for "labels" but that's just a single name-part and doesn't help here.)
(I don't currently have it installed so I don't have a handy answer to your command line question.)
