The final product. As Stan said, two inches of lift would be what was needed to move our Hawk from the old Tundra to the new one. But because of the way I have my jerry can support mounted under the wing of the camper, I needed to go at least three inches. The upper section is 2x4's that match the 1x4's that make up the footprint of the camper. Once that assembly was complete, I laid out a number of boards across the bed for the upper part of the platform to sit on.
I chose not to do a couple of things I thought I was going to do initially. I did not notch the lower boards to match the ridges in the bed for several reasons. I wanted water to be able to flow out of the bed and leaving the lower section of the bed between the ridges open will facilitate that. Also, that would have made the final platform a half inch lower, and I couldn't spare that. And finally, it would have been a lot of work I didn't have time to do.
I also did not put a spacer on the front of the platform to keep the camper back from the front wall of the bed since the camper already has bumpers on it.
I left the first and last boards of the lower section as 2x6's. This way I was able to notch them to fit exactly in the truck. Also the upper platform would sit back from the front wall three inches and the rear would overhang the end of the bed, so I needed a wider board up front to attach the upper section to and wanted as much support as I could get at the rear of the camper. All the boards in between are 2x3's ripped from the 2x6's.
Once all assembled in the bed, the platform can not move forward, backward, or side to side. It even needs to be partially disassembled to get it out of the bed. Here are the required photos.
The upper portion that matches the footprint of the camper.
The layout of the lower layer.
Front and rear boards trimmed to fit.
The final assembly.
Thanks again to everyone for their input. Maiden voyage is next weekend so I'll have pics of the truck after that.