I've been picking up on the hints left by the secret few.
In jp.co.polyphony.GTCourseMaker_1.0.2_NoChecks\assets\bin\Data\Managed\Assembly-CSharp.dll, inside EditMain.cs (line 612), I found:
if (!StaticObj.ࠧ)
{
this.ࡆ = AdditiveSceneType.HOME_STRAIGHT_SELECT;
this.StartHomeStraightSelect();
}
else
{
this.ࡆ = AdditiveSceneType.HOME_STRAIGHT_CREATE;
this.StartHomeStraightCreate();
}
Basically, it checks something, and then sets the state as either 'create' or 'select' home straight, and does the appropriate thing. Presumably, either it makes you choose a home straight from the list, or lets you place the home straight freely (for Eifel flat).
So, if I can make a small change to this code and rebuild the APK, we might be able to have free home straights on the elevation maps; and I have a feeling that this might also enable image import, which would be good, especially now we have these nice elevation contour maps
No promises, but I will have a go over the next week or so.