We go over there often. If I was coming from Chambana, I'd go cross country. Danville-Lafayette-Logansport-Rochester-Warsaw-Goshen-Middlebury.
Another good way would be US 24 to Ind. 15 at Wabash. Those non-interstates are going to feel slower, even though they are probably quicker.
For an interstate type route: I-74 to SR63 north into US41. Go north as far as you want before cutting over to I-65. SR 114 and SR10 are not as "big" as US 24, if you are driving a big rig you might stick to 24 to get to I-65. But 24 causes more of a backhaul on I-65. When you get to I80/94, stay on 94 east. Meaning, when the time comes to exit onto the tollway, don't. Get off at US 20 (Michigan City/Niles exit). Continue straight west onto SR 2, and turn right/south onto US 20/31 on the west side of South Bend. Zip around to the east side of Elkhart, turn east onto US 20 to Middlebury. No tolls on that route. And you'll miss all of the thickest NW Indiana interstate traffic. It is a lot lighter east of I-65.