Two ways to overcome that:
* In Target you can not only assign key presses and releases, but DX buttons and axes, too.
* In DCS you can assign missing keyboard commands then use those in Target.
Or: don't use Target as I do.
First you need to download them via the module manager.
Then you can create your own missions in the editor or fly instant action missions. When the instant action dialog is displayed you can set the map on the right side.
If you have the P-51 or Spitfire you could buy a scripted campaign that uses the Normandy map.
I can recommend the Big Show and the Blue Nosed Bastards.