Don't do it. There is a reason the LS (and other performance cars) use a 2-piece drive shaft. Research why the LS uses a 2-piece vs. a "normal" single shaft.
It's easier and cheaper to make a sloppy 2-piece then to balance a 1-piece precisely.
The critical driveline speed is higher on a 2-piece with the same specs as a 1-piece.
A 2-piece has more clearance then a one-piece (although I doubt it with an IRS rear)
Don't think I missed much. I'm just not a fan of the 2-piece design. At 41K miles mine needs a CSB or something already. Got a nice distinct humm/vibration at about 75 that is not tires/balljoints/alignment/rims/etc. Guess it could be CV Axles, but I don't hear that familiar clicking sound or other tale tale signs.