IMO Mindanao sucked as a map.
I've never seen the NW country get reset, S country always gets reset.
It really wasn't setup for GV warfare at all except for a couple of quickly taken fields. Once those are captured no more GV action.
As for the mountains thats fine for those that like them. But give me a nice sea level airfield with wide open planes to chase down those evil enemy fighters on!
You want Mindanao, start from scratch, rebuild it with mostly GV bases in the interior. Big bases around the perimeter, more ports, carrier fleets, etc.