I have never heard of anyone getting one to grow in zone 5, so probably not a good chance of it happening. I have tried several times (with winter protection) and still had no luck here in central Illinois. : (
In South Bend, you will be even farther north than I am.

I lived in Chesterton (near Valparaiso) a couple years ago and think that you should give it a shot. I suppose that it would depend on the variety of the Crape though. I live in Bettendorf Iowa and have been successful the last two years in getting my Southern Magnolias to survive. 2 Mag. Granifloras and one brackens brown beauty. Good luck.

I planted 3 crepe myrtles in S.E. Michigan 4 or 5 years ago -- 'Hopi', 'Zuni', and 'Apache'. They have survived, but die back to the roots every winter even with heavy mulch. One of them ALMOST bloomed a few years ago -- the buds started to open in early October and froze. The leaves are pretty, but I've given up on flowers.