I've been there many times. I'm pretty sure the only campground open at that time of year would be a KOA (if that's even open, I'm not positive). Most places don't open until April. You should go to eat at a place called The Essenhaus Essenhaus Amish Style Inn, Conference Center & Restaurant - Middlebury, IN
that has homestyle Amish food. It's really good. Also, if you feel like a side trip, the RV Museum is pretty close by in Elkhart http://www.rvmhhalloffame.org/
(along with a couple of fun RV Surplus stores!) The town of Shipshewanna has a lot of nice shops, so it's a fun trip. In the summer time they have a giant flea market every Tuesday & Wednesday, along with an auction every Wednesday. I'm not sure when they start that up again for the season. Have fun!