Once I liked the idea of adding NSA analogs like SF + FC and LC + RC, but I am not a fan of it for now. As Ege correctly stated, FC and RC are immense even without any additions; you spend a lot of time there on driving from one point to another, you've got lesser tactical options due to waste open spaces. Besides, hydras are extremely dangerous in NSA if used correctly, maybe it would be better in potential "Southwest San Andreas" and "Southeast San Andreas" due to sequoias, but, honestly, I don't want to check this on my own experience. Sometimes you need to wait hours for any city map.
So,
-1 with the current balance. I think that it would be possible if the balance is cardinally changed on such maps, but I don't know how. Maybe by adding seasparrows and jetpacks for everyone?.. And, of course, the distribution of maps appearance must be
uneven in that case, more favourable to the city maps.