You could build a frame like mine first. I made mine out of 1x2 wood at first to git some basic knowledge and dimensions. Moved on to 2x3 wood later. My bed rails were made with 2x4 that I cut to the proper angle after my first mockup...looks like you would have to either bolt through the top rails or use some clamps.
With the bed rails in place...you could experiment with a Kammback or a full cover...it would be up to yer budget and time.
