well, i didn't believe it but your numbers are right.
i apologize. apparently, R-Vision still has the lightest TT's made for their size.
that said, this is how the numbers work. your Nissan can tow a max of 6000lbs.
but that's with a 150lbs. driver and nothing else in the Nissan. anything else in it or on it, lowers the 6000 number. that includes the weight of the WDH.
most say that you should only tow 80% of the TV's max tow capacity.
and finally, the short wheelbase of the Nissan for such a long trailer, would require a Hensley-type of WDH. that's too much trailer for a traditional style WDH, for a short wheelbase v-6 SUV.
i tow a 23' HTT that weighs about 5000lbs. loaded for camping, with a 5.3 v-8 Chevy Avalanche.
and i wouldn't tow anything longer than 25' with it.
i would be scared ****less trying to tow a 31'+ TT with a v-6 mid-sized SUV, no matter how light it was!