Just depends on how much he wants to beat it and how the parts hold up. Rear wheel only will take the finesse out of the equation. We came out of Golden Spike earlier this year with RWD only in a built YJ, front was broken. We made it all the way out but it wasn't pretty. There was lots of wide open throttle, and carrying momentum while bumping and crashing over rocks. We did have a locked 60 in the back with hardened shafts and a well built Chev 350 motor, TH400 trans, and an Atlas.
Personally I'd never head out on those trails intentionally with that configuration, and would certainly not want to be part of a group with a rig like that. You can do it, but it will be a looong day and not too fun for those involved.