The PageMargins property works well.
RafaĆ Drzewiecki proposed to call the subproperties OffsetBottom, etc.Those names are better than just Top, Bottom, etc. Because they really are offsets.
The property PageMargins has a wrong name, in fact. If they are margins, you would expect left -4 and right -4 to decrease the margin with 4 on both sides. That doesn't happen. Because the values are really shift values i.s.o. margin values.
So, either PageMargins defines margins, or its name has to change into PageOffsets. The latter would cover the implementation nicely.