What width is available? Depending on the width, you could check out some of the taller purple-leafed Weigela or Physocarpus (ninebark) 'Tiny Wine' or P. Little Devil.

Thanks! I'll check into those. I think there's 12' or so available, both length and width.

Also consider Smoke Bush and learn about the differences in pruning for foliage vs "smoke."

There are some good varieties of Berberis that might suit. Barberries are tough and would take fairly low maintenance.

Barberries are invasive in many areas of zone 6, so you should check, either by doing a web search for your state name with the words "barberry" and "invasive" or by checking with your state Dept of Environmental Services or Natural Resources.

Here, smoke bush can be hard pruned annually to keep it shorter, but it will reach a bit over 4' by the end of the season, more like 6'.