You've probably just misunderstood how to go about setting a constant horizontal scale in your LookAndFeel: override drawLabel(). LookAndFeel_V2 has an example of this, if it helps.
As for your ellipsis: a new mechanism would need to be added to replace the call to GlyphArrangement::insertEllipsis() from within GlyphArrangement::fitLineIntoSpace(), and then some bool params would need to be added to control the showing of an ellipsis (to Graphics::drawFittedText(), to GlyphArrangement::addFittedText(), and then to GlyphArrangement::fitLineIntoSpace()).