BigAWB wrote:
What vehicle is best to pull behind a 38 ft Diesel.
With a DP, I would think you have a wide range of choices because your tow rating is probably higher than most gassers.  Of course you should consult your owners manual for your tow limits. :W 
Just like with every other choice in the world, it depends on your needs.  If you are just running errands like going to the store, a smart car (or it's equivalent) might work :h 
If you intend to explore off the beaten track, you might consider a 4wd of some sorts.:E
The 
dinghy towing section of this forum is a good place to look for more relevant comments. :S