If, when you say the D scale be between the strings, you are referring to the two high D strings (melody strings), there is a simple answer to that. Take one of them off, tune the one that remains, and play only with that remaining melody string. It will work fine. The woman I learned from taught me that, and I have been playing happily that way for years.

The way I figure it, if you have two top strings, every time you strike them, you hit the one close to you harder than you hit the second one. Pretty soon, the two of them will be out of tune, because the close one has been hit many more times.

As I said before, DAA is mellower and warmer. Also, the fingerings for making chords are simpler. What's to lose?