Mistakes! I hate them.

"This is for posterity, so be honest. How do you feel?" (Count Rugen to Wesley)

A little like swearing, actually. It turns out all of my planning and time figuring out tank configurations was wasted (I'm not too upset for a pun). All because I didn't know one small, yet game-changing piece of information.  

The "stringers" or small supports running lengthwise are unnecessary for the structure. The years prior to and after do not have them. Colin Hyde said that they routinely cut them out and use flat-iron.

Stringers

This means I could have cut them out and put wider tanks in the whole lateral space. Using the whole space means that I could have made the depth much smaller and fit the tanks inside the belly pan itself.  My plan exposes the narrower, deeper tanks under the belly pan. This makes them exposed to road debris and camping/parking objects, like stumps. 

Of course, I didn't learn that the stringers could be cut out until after the non-returnable tanks have shipped.

"Fezzik, do you hear that? That is the sound of ultimate suffering." (Inigo to Fezzik)
I may be mixing up my theme...