Here’s a screen shot of the progress I’ve made on the Sketchup.
You’ll notice I have spare lumber pieces next to the house. I found it easier to copy and paste boards that were already oriented the way I want them.
I’d find it a lot easier to move around and measure an actual model. If you’d like to work with this model, the file is here:
One caveat is that you ought to measure your trailer before cutting boards. An inch here, an inch there, and everything could get off.