The nature of unpack means it supports variable width final columns, they will show up as an empty string by default or undef if you enable the option.
The lack of headers is an issue, the biggest time saver of using the module is not having to count the chars for the unpack template by hand -- I might be able to make this work with heuristics if you send in the whole table though -- I'll have to look at it.
The stripping piece is all done by the user, we don't touch the file handle. You send to me the line to process.