this will get you in the ballpark. i'm not sure about the malto dextrine. Never put anything like that in my beers (which I have taste-tested against franziskaner, and it's very close, but franziskaner is not really my favorite hefeweizen anyway). I also use less hops in mine, but I was using fairly hard water and not correcting ph, since it's much less of an issue with hefeweizen.
In 6 years of living an hour from munich, i never really tasted *any* hefeweizen that anything I would call hop character, so I use only 60 minute hops.
For me, the key has been fermentation temperature control. All my best and most authentic hefeweizens have fermented at 62-64 degrees. The ones that up towards 68-70 are the ones that turned out thinner, excessively estery, less body, and just less authentic. If you do water adjustment, I would stay on the higher side of mash ph than you would normally do for such a light beer.