This view shows you the loose mock-up of the racks and an old pallet thrown on the cross-beams to simulate the height. The brown cylinder is the proposed placement of the smokestack. I am thinking it's too far forward, but maybe when the frame is built around the cab it will be more clear. The height of the beams is currently at 5', and we did try putting them at 6'. Ideally, higher would give a better view and allow people to use the space under the decking. But once we were up that high (10 feet off the ground), the truck could be easily swayed by just one person. The railings were also only 2.5 feet, which made it feel really unsteady. The platform is now at 5 feet and that seems about right for this size of truck. Maybe next year ambitions and construction skills will be for something bigger and higher, but this is it. After setting the height, I then had to notch the uprights to make them fit with the bulkhead of the truck bed. Here's the final positioning after the cutting:
Here's a view from standing on the new platform. You can see how the framing of the bulkhead on the truck fits nicely with the new pallet rack structure. The notch was required at the base.