I am suggesting a very simple utility- Simply make a version of the little route map and profile in the route preview that is a separate utility. It should be as big as the RouteViewer is.

Even better, add zoom in/out.

Could help in checking curves, relative distance, etc.

Interesting idea and the code mostly around there; perhaps it would work as part of the RouteViewer utility itself, rather than needing yet-another-program.