Hm. If Verdanturf is significantly closer to Mauville, it should mean that the mountain range is broader, and Rusturf Tunnel many km long. Or, alternatively, Route 116 to the east of Rustboro could be considerably longer than average... Or both. 

I could see expansions of some of the more wild areas of the region, like the Route 111 desert north of Mauville and Route 124 between Lilycove and Mossdeep. It should be a real trek to get to Lavaridge/Mt. Chimney from Mauville, I think. Perhaps the Petalburg Woods as well, extending through that entire stretch of forest north of Petalburg. I don't know. Things to think about, for verisimilitude. 

(I make my own maps for my D&D games and other RPGs, so I have a good distance sense most of the time.)