Your key layout is just about right. The "lower" row of keys play the major scale for the tuning, so a G/C instrument locates the C major scale on the lower keys. This, of course, has not sharps or flats so is just like the white notes on a piano. A D/G instrument locates the G major scale on those keys, so you get one sharp - F-sharp - on that row.
The penultimate highest key in the D/G tuning can be tuned to C or C#, and on many (all?) instruments can be "bent" by finger pressure between these two, but you are very close to the wheel here so you are moving the string across the wheel surface noticably further in this way, changing its attack, wheel pressure and all sorts of other things that affect the quality of those high "dusty-end" notes.
Oh and one other thing - whether this transposition is a fourth or a fifth depends on which D chanterelle you are starting with compared to G.