My brother built this one many years ago. He had three kids so he also added a tilt out rear bed.
When I was thinking about building my own, he gave me the set of plans. The set had the small plans but only one side wall sheet of the full size plans. Not sure what happened to the rest.
No doubt the full size plans will help if you go that route.
Beside some of the common sense changes and material changes you mentioned, I would have to change the slant of the front cap for more aero dynamics. Just a preference.
He carried it on a F250 camper special. Said it did a great job even as big as it was. His son still has the truck.
I'd still like to build one but the wife frowns on it. She'd rather use it than work on it. She just doesn't get the "I built that" enthusiasm, says it's just more work.
Although, she does appreciate me when something needs to be repaired. tends to point me right at it.
Good luck,
