After have played this map, I strongly believe that some changes have still to be done in order to fix the gameplay.
I am asking sorry from now if this idea has already been proposed, anyway I think I got a good solution for this map.
The graphic has been changed with paint, I guess the map maker could do a lot better than me:
Introducing a connection between Diana (or Sava) and Androy (or Tulear) and reducing some bonuses fix map gameplay without any need to increase the bonuses.