How about making the fortifications a little more interactive. It think it would be fun as the germans planning the atlantic wall and as the french improving certain aspects of the maginot line.
For example for coastal forts rather than just improving level 1, level 2 etc. you could choose specific fort improvements: mines, anti tank, barbed wire etc that all added to the defensive modifier but cost different amounts and took longer or shorter to build depending on the improvement.
Same type of thing for land.
If the provinces were smaller it might be possible to plan right down to putting gun batteries in place and the site of concrete fortifications?
For example for coastal forts rather than just improving level 1, level 2 etc. you could choose specific fort improvements: mines, anti tank, barbed wire etc that all added to the defensive modifier but cost different amounts and took longer or shorter to build depending on the improvement.
Same type of thing for land.
If the provinces were smaller it might be possible to plan right down to putting gun batteries in place and the site of concrete fortifications?