Weeell... after hours of intensive design work, more hours of measuring, measuring, measuring, cutting and welding... the damned thing don't fit!
Testing the stability...
Grinding down welds on the underside of the framework.
At least I was able to calculate a weight for the boat: 618 pounds. The framework added about 128, and the trailer itself is probably about 250 pounds, for a total of 996. The legal limit for an unlicensed trailer in Oregon is 1800, so it fits that, but it's getting too close to the 1200-pound towing capacity of the Nissan... . All that aside, the Honda Civic springs I used to build it were bottomed out with all that extra weight.
After a redesign and rebuild I think I can get the sprung weight of the trailer down to about 200 pounds, for a total weight of around 900. Stay tuned... .