[Dingfodgy]

I'm not totally clear on what the question is, but it sounds like you are concerned about putting the front sheet metal back on the truck as individual pieces rather than a complete sub-assembly after painting? If so, you should be fine as long as you're careful and take precautions against scratching fresh paint. Matter of fact, I would suggest painting the cowl, inside of fenders and bottom of hood first. Then reassemble the front sheet metal to spray the outside of the truck. Same with bottom of cab, door jambs, back of cab, bottom of bed, etc, etc.
I would venture to say that nobody on this site has this front-end assembly jig thingy shown in the manual.

Lemme know if this answered your question or if I totally mis-understood what you were asking.