Check out minicpan. It allows you to save a complete copy of the CPAN (which includes only the most recent release of each distribution) locally, which you can then copy over to your offline systems, and use it as if you were using the online version.

I've never used it myself, but I know others who have, and it's specifically used for situations such as this. With one person I know, they have used it for years so that they can do testing and development while on flights (nowadays airlines have onboard wifi for the most part, but I digress).

Perhaps some of these users can speak up with their experiences.