I followed a couple down the tenn-tom in a 24' sailboat. They broke their rudder when caught between a barge and a speeding powerboat, so be careful of the water turbulance you put that small rudder in as there isn't a lot of room when many boats trying to speed on by and a tug going the other way.
As for the space, well, they were very much in love so the tight space was pefect for them.
Just want to echo the "do not travel at night". There is no light out there and the tall trees make it even darker. There is a marina at the start of the tenn-tom that sells the charts...I think about $35. You really don't need them though as they don't give you any information of the floor. Only real good thing they are for is planning where to stop, but mostlikely, you will be traveling with a group as the locks tend to wait for everybody before they open up, so you can just follow them. If nobody to follow, then definately get the charts.