It has been many years since I last saw the upper part of the Mississippi river, south of Memphis there is little access to the river except the handful of major bridge crossings. I would suggest you consider taking a side trip over to follow the Natchez trace parkway at least part of the way (think of it as a national park that is 300+ miles long and half a mile wide with a 50 mph speed limit. Take a side trip and spend half a day touring the battlefield in Vicksburg, and if you can spend some time in Natchez. Going south from Natchez stay on the east side of the river, it is much more scenic than the west side. When you get to New Orleans remember it has one of the highest violent crime rates in the country, the police do a good job of patrolling the tourist district, but be aware of your surroundings.