I wanted to circle back with you about the fit of the Co-op Cycles DRT 4.1 fat tire bike. I swapped my stems out today and it was exactly what I needed to dial in the proper length for me. It's definitely worth considering if you feel like the cockpit of the bike isn't quite long enough. I happened to have the right stem on a different bike, but I'll probably grab a new one anyway (as my other bike is now too short), should be a pretty easy part to find at your local bike shop.
Hope this helps, enjoy your ride!