Our "home campground" in the Montgomery area is Fort Toulouse campground. It is a COE park (leased by the state since it adjoins a state historical site). In typical COE fashion it doesn't have sewer hookups but does have a dump station. Rates are $15 a night, $12 for seniors or military.
If you stop in, tell Nathan the camp host that the Talleys sent you.
if you are looking for a quick off and back on site near I-65, I've heard decent reviews on Montgomery South RV Park. Depends on if you are heading cross-country on US 231 to FL or not, though, to be considered "along the route".