You would probably need to do a 2 piece driveshaft. The stock rear shaft is already ridiculously long. If memory is correct, the place that built my driveshafts after my axle swap said that they won't build any driveshafts with more than 4 foot of tube, and mine was very close. I believe the extended cab 2wd trucks had 2 piece shafts with a cv in the middle.
Personally, if I was doing what you are wanting to do, I would probably get it all done, take it out and get stuck in wet grass and wish I'd of left the 4wd
Other than that, I'm not much help.