Two boxes, one for the freight and one for the palace could work, I would think. Just allow for room between them for when the air bags colapse. You need to leave 3 to 5 inches between the components to keep them from damaging each other.
We have a five-inch gap between the cab and sleeper and a three-inch gap betwen the sleeper and the box. When we drain all air out of the system, or when it slowly leaks out by itself as the truck sits, everyhing settles in just fine. But if the gaps were too small, problems could arise, both when the truck sits or when it is moving.
The reason for a five-inch gap between the cab and sleeper is the Volvo day cab has a forward slope on the rear wall. The sleeper manufacturer built an adapter frame for that space to square off the cab wall and mount the boot.
You already know the palace box and freight box walls will be true vertical. Before starting to build a palace in a box to place on a truck, a plan must be developed to mate the front palace wall to the rear cab wall. For that, you will need to know the characteristics of the cab you plan to use.
We have a five-inch gap between the cab and sleeper and a three-inch gap betwen the sleeper and the box. When we drain all air out of the system, or when it slowly leaks out by itself as the truck sits, everyhing settles in just fine. But if the gaps were too small, problems could arise, both when the truck sits or when it is moving.
The reason for a five-inch gap between the cab and sleeper is the Volvo day cab has a forward slope on the rear wall. The sleeper manufacturer built an adapter frame for that space to square off the cab wall and mount the boot.
You already know the palace box and freight box walls will be true vertical. Before starting to build a palace in a box to place on a truck, a plan must be developed to mate the front palace wall to the rear cab wall. For that, you will need to know the characteristics of the cab you plan to use.