I don’t know anything about the area you mentioned. I do know a way you probably can get a map, and not get lost. Go to this website http://terraserver-usa.com/default.aspx
They have aerial photos and USGS topo maps of the US. You can zoom in as tight as 1 meter resolution on the aerial photos and print out the view. When you go to print it, a new window will open. There are several options here for page size and orientation. You can also put grid lines on. This is the good part. The grid lines give locations in Longitude and Latitude. They do so in three different forms: Degrees, minutes, seconds; Decimal Degrees; & UTM. They use the NAD83 datum. So once you find the area you want to navigate you just print I out with grids. Set your GPS to the NAD83 datum and away you go.
When traveling over a larger area, I find it best to print out from an 8 or 4 meter resolution with grids on an 11 x 17 sheet of paper. I did this and was able to successfully navigate the Wolf River between New London and Oshkosh. The whole while I knew exactly where I was and how far away the next gas station was. I was also able to find the back water sloughs which are just out of eyesight from the river. You can get by with 8-1/2 x 11 sheets too.
The aerial pics are great for finding hunting spots too. This won’t help with navigable channels, but it will help prevent you from getting lost.
I hope this helps.