The main channel is minimum 9'. Its the anchorages that get difficult. There are many stretches with no good marinas.
Have you checked with Hoppies on the Mississippi? You MUST verify they have the depth to accommodate you. From Hoppies its 250 miles to the next stop. Without them it will be much much longer. Do you have capacity to make 250 miles? There are no fuel stops in that stretch.
Most of the locks have floating bollards. They make life very easy if you have a mid ship cleat. Pull into the lock, loosely tie one line around the bollard from the mid ship cleat. Send one person fore and one aft to lightly fend off. Very easy once you get the hang of it. Be mindful that the bollard can get stuck! You'll need to untie FAST if that happens!
2 vhf radios are nice. Ch 13 to talk to the tows and 9 to talk to the locks. Sometimes you will be doing both. Learn the lingo of the tows and they will be very helpful. Speak 'english' and they'll ignore you!! This is important.
You need army chart books for the rivers.
Have you looked into the aglca? You will find much more info there than here. Any Great Loop resources will be good. Also mtoa.