Dry Box Organization
I'd like to thank everyone in this thread for sharing their ideas and thoughts. Based on the ideas I saw here, I ended up building my box organization around routered 1x2, 1x4 and 1x6 for fillers and 1/4" dividers cut full height, lower/upper height and middle height. I'm pretty happy with the result, as it allows me to create different height shelves and compartment widths in 2" increments. I made the shelves ~6" wide, and they lay in on top of the router 1x2.
I used a 5/16" router bit for the 1x2 routers, which receive the 1/4" dividers.
Working from the bottom up, I stacked: 1x2 + 1x4 + 1x2 + 1x6 + 1x2 + 1x4 + 1x4. I then shot the 1x2 + 1x4 together with a nailer, the 1x2 + 1x6 together with a nailer, 1x2 + 1x4 + 1x2 together with a nailer. I then just slide the 1/4" dividers in to hold everything together.
The end result allows me to have deep storage, shelves/compartments to hold stuff that is not used very often (valves, repair kits, rain gear, first aid, etc), and then stack stuff on top.
Again, thanks to everyone in the above thread for their ideas. Can't wait to get it on the river.