I haven't had trouble getting people to make longer drive shafts.
You should see the drive shaft on my neighbors F350 crew cab long bed.
I bet that thing is longer than my whole C10.
I've seen them on ebay over 140 inches long.
http://www.ebay.com/itm/2002-Ford-F2...8a15df&vxp=mtr
However... a one piece on a short bed with stock height can be done.
Long bed makes it tougher. Dropped 5 inches ever harder. A guy I have been working
with here in town had to buy an after market trailing arm cross member, and then
had to modify it even further by extending the drive shaft loop down another 2 inches.
He said if he had to do it all over again... he would go two piece.