Well there is a solution to this without going overboard.
1. Use the RoN 'border' system - this means you can only build in the area you currently control
2. Make it so that, once you have no units left, you are defeated. However, if you have unit-prouducing buildings left, you lose when you run out of money
That way, you cant just build anywhere on the map, and you cant hide buildings to make the game never end.
Dark Lord of the Purists
Inter Arma Enim Silent Leges