Technically, we are not allowed to store trailers or boats outside of our garage. Since our back yard faces a popular path for runners, pedestrians and cyclists, I came up with this solution and we have not been reported.
The size isn't ideal (peekaboo canoe), but I went with boards I already had. I didn't sketch this out ahead of time, just pieced it together using a 6" board as my vertical guide and a 3" board as my horizontal guide.
Instead of digging post holes, I built it onto feet so that it's free-standing and portable. We can move it any time we need to get the trailer out from behind it.
Next summer, I may put planter boxes on top and build a second panel as well.