Here's the chassis plan. Some modifications from Andrew's plan, apart from increasing the width 2 inches and the length by 13, include the relocation of the axle 10 inches forward to account for the reversal of the galley and the addition of another angle cross brace under the most trafficked area of the floor for more stiffness and for a place to attach bands that will support the holding tank.
I wonder if these small changes in dimension are sufficient to warrant the larger longitudinal box sections of 3 x 2 rather than the Compact III size of 2 x 2, especially since I doubt that my build will be much heavier than Andrew's original conception. I'd sure like to gain that extra inch in interior height if it doesn't compromise structural integrity.