20 regions only ? 0_o
Wow, that really seems very few. It may be to emphasize the "field battles" aspect, but I'm not convinced at all it won't simply ends up in a massive simplification of the game - at least of the strategic map.

The problem with the map is the same than every single strategy game has encountered, and nearly no one ever bothered to implement : logistics and attrition. It was attempted in NTW, but from what I heard, it was a missed occasion and it became quickly irrelevant.
Make armies on the move take a little casualties each turn, and increase significantly these casualties depending on their situation (no supply lines => much larger attrition ; hostile territory => larger attrition ; hostile terrain (like desert) => much larger attrition), and you will quickly have much more realistic strategic-scale situations - like not having anymore these full-stack armies in the middle of nowhere that just walk around without purpose for decades.

But, for a reason I can't fathom, supply lines and attrition are elements that are nearly never used - and the few times they are used, they usually are completely OVERused, like in many Paradox games where any significant army just melt in two turns due to exagerated attrition.