Just pull the seats, and pull the carpet forward (theres not much carpet behind the seats) and put a tarp over the dash and you'll be fine. You should be able to do it in under 6 hours start to finish.
Yeah. I work 12 hour days so maybe two 3 hour days But I wouldn't have to make that drastic of a tunnel. You know what guage the sheet metal is on the cab off the top of your head?