Why not flat tow it? You'd have to research whether BlueOx or Roadmaster makes brackets and get that all set up but I routinely flat tow my cars and will never own another monstrous car trailer. Where are you going to park it when you're camping/etc?
I've flat towed a Jeep across the country with a 5.4 EB and only lost 1 mpg. You're diesel wouldn't even know it was there.
Thanks Scotty I thought about it, but my concern is wear on the smartcar. I was hoping the trailer can be light enough to move around easily, perhaps that is not the case. You have a good point about what I will do with the trailer once parked. most of the time I guess leave it attached if there is room but otherwise I don't know yet. Thanks for all the comments!