Just discovered my center support bushing is disintegrating. Before I order the replacement, does anyone make a one piece shaft? Ive gone down the google but figured I'd ask here before I write the idea off.

 

None commercially but a guy here in Oz has had a 1 piece shaft made and fitted, i was surprised there was enough room as the shaft doesn't run straight pinion to pinion as it has a kink where the fuel tank is.

 

If you decide to keep the 2-piece driveshaft,(recommend this) inspect it carefully before reinstall. Had a center support bearing fail on a BMW a few years ago. Root cause was a failing u-joint: not loose(yet), tight, causing side loads on the bearing. Thanks to non-serviceable, staked in u-joints, it got a whole new assembly for $700.00.
New bearing doesn’t cost that much, no real reason to re-engineer a solution when the rear dif doesn’t move with suspension articulation.
If you do go the custom route, make sure the shop you use can balance the shaft. This will be critical with the new longer shaft.
In the jeep world, Tom Woods driveshafts is a well known name with a good reputation. If they haven’t made the shaft you need they will work with you and they know what they’re talking about.