I know a few people that run square driveshafts on the road... haven't heard any complaints from them.
Being raised a Chevy man (for the record I think all the domestics are about equal in reality) I can't resist pointing out that Ford trucks are often behind tow trucks so having a square driveshaft wouldn't be much of an issue.
Found On the Road Dead
Forward Only Rolling Downhill
F'd Over Rebuilt Dodge
Fixed Or Repaired Daily
I know a horrible one for Pontiac (that I won't post), but I can't remember ever hearing any for Chevy, Dodge or Toyota, has anyone else?
I can't imaging that a square driveshaft would be much cheaper than shortening the one you already have and I would expect it to induce terrible vibration on the road. You might get a set of Swamper Boggers and then you might not notice.