Extended roof internal supports

I am seeking any accurate information or schematics showing the exact locations of the metal framework inside my 2005 Ford E350 van’s extended top. My thought is to use this framework to anchor cabinets to.
Any leads?

Bumping for ANY awareness.

Do u have any references to the side wall braces going up the wall. If so the extended roof should follow the same for structural integrity

The interior and exterior surfaces are smooth and somewhat featureless. I do know that there has to be a rigid metal skeleton supports between these two surfaces, I just don’t know where they are and I don’t want to drill a host of pilot holes looking for them.

On the bright n side of the van if walls are not installed you should see supports . If walls or paneling is installed I’d check with a dealer. Ask the service manager if he or she can help you out. If that doesn’t work go to you tube and resource. If all else fails do a tap test with a screw driver handle. You should be able to tell the difference I sound. Start on the walls first then track up towards the roof.

Thanks Doc. All good suggestions.
This pop top is basically two plastic/fiberglass bowls one nested in the other (forming the outside walls/roof and inside walls/ceiling) with the skeleton between them. No seams. Too thick for light to penetrate. I’ve tried knocking on the walls to “find a stud”, tried several different studfinders, tried pushing to determine where resistance is stronger, all with the same results, nada!
Scratching my head……

With no ceiling structure to attach your upper cabinets to, you could put brackets on the wall supports, when you find them, and drop posts (or side panels) down to the floor. Upper cabinet weight will put rotational forces on the walls they will bow inward which could compromise your ceiling seal and the roof shell. Particularly if you go over significant road or off road bumps.
The next question is how long a cabinet run do you want? Are you going above a 75” queen mattress with cabinets above? You will need to span the posts with a beam that could be wood, aluminum or steel for a long set of cabinets.
If the cabinets are going back to and above the rear doors there may be door header frame that you can reinforce to support one end of the cabinet run. Even with diagram specifications of your van walls you will have to visually expose the structure that you will secure to. Cannot just drill and screw through your finished walls hoping to hit adequate structure.
You have lots of head room and you want to use it, understood. We are really just talking about a frame to support your overhead cabinets.

Thank you EzShot. Over the back doors is a no-go as the back ceiling area is occupied by an AC unit.