https://www.warlight.net/wiki/Mod_API_Reference:Game implies there will be commands for changing a map.
That page is saying that data about the map is readable. That's there now, but it isn't writable, and isn't documented yet.
The MapDetails object will never be writable as that's specifically data about a map, which could be shared between many games.
In the next update we're adding the ability to set overridden bonuses, but only at game creation.
In the future, we hope to add the ability to override the income calculation, which would allow you to determine each player's income based on any formula you wish. I think that's what would be needed to do this idea. This hook is a ways down the list at the moment though.
Edited 4/6/2017 20:32:35