Building a Laser Trailer

I have started to work on building a box on top of my trailer for storage. It was very cold and windy but with a new baby, work and law school I have to make the best of whatever free time I have. The plan is to build something similar to this trailer:
My trailer is not as wide and does not have a rectangular shape, so I am modifying the design on the fly. Based on a suggestion from Tillerman, one side of the box is on a hinge so I will be able to get gear out of the box without taking the boat off the trailer.

Here's the trailer before:

I bought three 8' 2x6, four 2'x4' plywood panels and some other assorted wood.

I attached the hinged side first.


Then the other side and the cross pieces.

It started to get dark before I could start trimming the plywood so the rest of the project will have to wait for another day.