Looking great, Igor! I've been checking on this thread just about daily since you first posted it, very excited to see the finished product.
My question, have you considered moving your assets to the map "Desert" ported from Arma 2?
The map is essentially endless if you don't mind building beyond the map screen. I've been toying with my own western map since finding this thread, using the mods you've listed; though I've had little time to do so unfortunately. It's all very WIP.
http://imgur.com/gallery/8jvBy
Again, really looking forward to see what you come up with! :)