This is something I've been cogitating on for awhile.
Some of my previous suggestions (spells that change map files etc have touched on it).
You can get 80% of the way there now, and get 100% of the way with a few modifications.
What would need to occur is the game host, instead of sending .trn files, would send encrypted executable files.
The executable would:
unzip the trn, the map, and the mod files
run dominions
(modification
Upon quiting exit back to the ap, not the window)
(optional: submit the .2h)
Delete the .map and the .dm files)
Quit.
But this kind of approach would allow all KINDS of neat new features: Expanded random events. Terrain changes to map files.
etc.