to place a reference plane at a certain distance and a inclination, do you have to create others?
to have the dtm2 plan passed for the creation of the dtm1 rotated ... is there a way to create a single plan in the desired location?
Yes, there is no other way if we talk about mere references.
there are several strategies however to avoid many references, but these are learned with time.
one that I suggest is for example to use points with coordinates, or sketch ad hoc.