Put all your .deb - files in a directory "pool" , say /path/to/debarchive/pool
Run this on a shell:
$ cd /path/to/debarchive
$ bash mkdebarchive.sh

* disconnect Network
$ apt-get update
$ apt-get install <stuff>
* win, win and win again.

TODO: Order of APT source files. /etc/apt/sources.list seems to be prefered
      over any /etc/apt/sources.list.d/foo.list .
      Maybe workaround: clear /etc/apt/sources.list; move contents to
                        /etc/apt/sources.list.d/99original.list .