Bedrails on Rambox trucks

[mountainears]

I posted previously the prototype of these bedrail spacers I was designing to 3D print, one of those pics is below. I've since evolved the design and I think I'm ready to go to the ASA filament once it comes for a final version.
The problem I'm solving is trucks with Ramboxes, the bedrails on have an extruded lip that makes it impossible to mount anything with a flat face using standard t-slot nuts. You can see how the rail sticks out in that early prototype I made with the green PLA that came with my Bambu X1C printer. The new design is using a large t-slot nut that I inserted during a pause in the print, it floats in the print and it provides a solid metal surface to lock things in and now I have a nice flat surface to mount stuff. First thing going in is a large water fire extinguisher horizontally on the rail but I have plans for some d-ring mounts and a molle panel extension.
This is my first week or so 3D printing and using Blender for CAD design, all new stuff. Between YouTube, ChatGPT and the amazing tech of these printers it's just crazy what you can do. Looking forward to solving more problems, I've ordered a second printer because I have a lot of plans....

 

[mountainears]

EDIT / UPDATE TO ADD PHOTOS OF THE MOUNT / APPLICATION: I used the prototypes that are in PLA to temporarily mount the empty extinguisher to show what my intended end point looks like, might provide a little more insight into the structural nature of things and perspective on size of the extinguisher (rechargeable water can). As noted below, the plan is to reprint these in the more suitable ASA when I receive that material. Also showing the bare rail with the protrusion that makes it impossible to mount something flat like this.