An auto would be even more of a slug.
Even on the level, you would not be happy with the lack of true power and responce.
A trailer would mean more weight to pull with not enough power. And, perhaps poor handling. The chassis might have adequate springs but the medium duty cabs don't ride or handle as well as a heavier cab would.
The DT466 is not the same as a 7.3 or 6.0 Ford pickup engine. See
http://www.internationaldelivers.com...t466detail.asp
I might also mention, you will have more engine and road noise to contend with.